Since you already had exported your table to .png with enough resolution for medium quality printing, it might be simpler to include it as an image.

            documentclass[letterpaper]{article}
            RequirePackage{graphicx}
            usepackage[margin=.9in]{geometry}

            begin{document}
            includegraphics[height=textheight]{9ph4R.png}
            end{document}

You can also export a selection of a word document to pdf. After export, you need to crop the resulting pdf with pdfcrop or epspdf (command-line) or epspdftk (gui).

I tried to save the Word file as html and used the following Python script to convert html to LaTeX. It is still different from your original design, but I think you can build from here.

from bs4 import BeautifulSoup
from pylatex import Tabular, MultiColumn, TableRowSizeError, NoEscape

with open('Table_Synthesis_for_SO.htm', 'r') as infile:
    htm_src = infile.read()

soup = BeautifulSoup(htm_src, 'html5lib')

table = soup.find('table')

latex_special_chars = {
    '&': r'&',
    '%': r'%',
    '$': r'$',
    '#': r'#',
    '_': r'_',
    '{': r'{',
    '}': r'}',
    '~': r'textasciitilde{}',
    '^': r'^{}',
    '': r'textbackslash{}',
    '-': r'{-}',
    '[': r'{[}',
    ']': r'{]}',
}

def escape_latex(s):

    if isinstance(s, NoEscape):
        return s

    return NoEscape(''.join(latex_special_chars.get(c, c) for c in str(s)))

def extract_text(element):
    res = []
    for p in element.find_all('p'):
        text = escape_char(escape_latex(p.text.strip()))
        if len(text) > 0:
            res.append(text)
    ret = '\ n'.join(res)
    return 'makecell{%s}' % ret

def escape_char(s):
    return s.replace('?', '$gamma$').replace('σ', '$sigma$')

tabular = Tabular('m{5cm}' * 4)

trs = table.find_all('tr')
for tr in trs:
    col = []
    tds = tr.find_all('td')
    for td in tds:
        text = NoEscape(extract_text(td))
        colspan = int(td.attrs.get('colspan', '1'))
        if colspan > 1:
            col.append(MultiColumn(colspan, align='c', data=text))
        else:
            col.append(text)
    while True:
        try:
            tabular.add_row(col)
            break
        except TableRowSizeError:
            # manually insert something in second row
            col.insert(0, '')

with open('tb_src.tex', 'w', encoding='utf8') as outfile:
    print(tabular.dumps())
    outfile.write(tabular.dumps())

The resulting TeX source is:

documentclass[11pt]{article}
usepackage[landscape, margin=1cm]{geometry}
usepackage[T1]{fontenc}
usepackage{amsmath, amssymb}
usepackage{array}
usepackage{makecell}
usepackage{newtxtext, newtxmath}


begin{document}

{tiny

begin{tabular}{m{5cm}m{5cm}m{5cm}m{5cm}}%
makecell{}&multicolumn{3}{c}{makecell{General
  Output Format :  (a/b) (c/d) {[}e,f{]} 
1) First
  couple of values : Without $gamma$
   (a / b) 
2)Second
  couple of values : With $gamma$
   (c / d) 
3) Inside
  each couple of values : (a1 / b1) = (FoM(10 bins ) / FoM(11bins)) 
4) Inside a
  couple of values  for GCsp: (a2 / b2) = FoM(4 bins) /FoM(5 bins) 
5) Standard deviation for each $gamma$ case (within brackets) : $sigma$ on (c,d)  $gamma$ cases {[}e, f{]} = {[}$sigma$c, $sigma$d{]}}}%
&makecell{Pessimistic (IST case): 
kmax = 0.25 h.Mpc{-}1 
lmax(WL) = 1500 
lmax(GCph) = 750 
lmax(XC) = 750 
sig_p, sig_v to estimate 
Zcut for GCsp combined with GCph}&makecell{Semi {-} Pessimistic: 
kmax = 0.25 h.Mpc{-}1 
lmax(WL) = 1500 
lmax(GCph) = 750 
lmax(XC) = 750 
sig_p, sig_v to estimate 
No Zcut for GCsp combined with GCph}&makecell{Optimistic (IST case): 
kmax = 0.3
  h.Mpc{-}1 
lmax(WL) =
  5000 
lmax(GCph) =
  3000 
lmax(XC) =
  3000 
sig_p, sig_v fixed 
No Zcut for GCsp
  combined with GCph}%
makecell{GCsp {-} No $gamma$  (4/5 bias) 
GCsp
  {-} $gamma$
  (4/5 bias)}&makecell{(14.18 / 13.81) 
(7.39 / 6.84) 
{[} 0.182 , 0.181{]}}&makecell{(14.18 / 13.81) 
(7.39 / 6.84) 
{[} 0.182 , 0.181 {]}}&makecell{(56.14 / 52.61) 
(37.73 / 34.48) 
{[} 0.136 , 0.133 {]}}%
makecell{Number of photo bias : 
(No spectro bias here)}&makecell{Pessimistic: 
(10) / Extended (11) 
Zcut < 0.9}&makecell{Semi{-} Pessimistic case = 
Pessimistic (IST case): 
(10) / Extended (11) 
No{-}Zcut}&makecell{Optimistic (IST case): 
(10) / Extended (11) 
No{-}Zcut}%
makecell{GCph}&makecell{(1.69 / 1.69) 
(1.10 / 1.10) 
{[} 0.466 , 0.466 {]}}&makecell{(4.25 / 4.93) 
(3.15 / 3.78) 
{[} 0.429 , 0.409 {]}}&makecell{(61.80 / 66.55) 
(55.08 / 59.48) 
{[} 0.129 , 0.128 {]}}%
makecell{WL}&makecell{(24.09 / 25.72) 
(7.13 / 8.01) 
{[} 0.191 , 0.180 {]}}&makecell{(24.09 / 25.72) 
(7.13 / 8.01) 
{[} 0.191 , 0.180 {]}}&makecell{(46.82 / 50.65) 
(13.97 / 15.61) 
{[} 0.09 , 0.08 {]}}%
makecell{GCph + WL + XC}&makecell{(211.52 / 213.50) 
(75.70 / 77.80) 
{[} 0.079 , 0.077 {]}}&makecell{(358.41 / 382.86) 
(128.96 / 142.14) 
{[} 0.062 , 0.058 {]}}&makecell{(1006.13 / 1035.82) 
(441.97 / 477.52) 
{[} 0.021 , 0.020 {]}}%
makecell{Synthesis with simple sum (GCsp+GCph+WL) and 
GCsp+ (GCph+WL+XC)}&makecell{Pessimistic (IST case):  zcut (5 first bias for GCph) Zcut <
  0.9}&makecell{Semi{-}Pessimistic
  case: 
(10) / Extended (11) 
No{-}Zcut}&makecell{Optimistic (IST case): 
(10) / Extended (11) 
No{-}Zcut}%
makecell{a)       
  Specifications IST : 
·         
  (4 bias spectro) : 
GCsp + GCph + WL}&makecell{(121.73 /
  125.30) 
(99.81 / 102.38) 
{[} 0.036, 0.035 {]}}&makecell{(151.05 / 156.16) 
(119.72 /127.41) 
{[} 0.035 , 0.035 {]}}&makecell{(351.18 / 367.42) 
(262.88 /279.53) 
{[} 0.018 , 0.017 {]}}%
makecell{b)       
   Specifications IST : 
·         
  (4 bias spectro) : 
GCsp + (GCph + WL + XC)}&makecell{(384.80 / 386.64) 
(255.84 / 257.64 ) 
{[} 0.031, 0.031 {]}}&makecell{(550.01 / 573.48) 
(320.07 / 333.93) 
{[} 0.029 , 0.028 {]}}&makecell{(1220.39 / 1249.97) 
(692.62 /725.96) 
{[} 0.016 , 0.015 {]}}%
makecell{c)       
  New specifications 
·         
  Bias independent : 
(5 bias spectro) : 
GCsp + GCph + WL}&makecell{(119.67 / 123.34) 
(99.20 / 101.84 ) 
{[} 0.035, 0.035 {]}}&makecell{(146.68 / 154.12) 
(119.72 / 125.45) 
{[} 0.035 , 0.035 {]}}&makecell{(340.83 / 357.19) 
(255.68 / 272.10) 
{[} 0.018 , 0.017 {]}}%
makecell{d)       
  New specifications 
·         
  Bias independent : 
(5 bias spectro) : 
GCsp + (GCph + WL + XC)}&makecell{(389.00 / 386.80) 
(259.32 / 261.08) 
{[} 0.031, 0.030 {]}}&makecell{(548.22 / 571.35) 
(320.84 / 334.05) 
{[} 0.029 , 0.028 {]}}&makecell{(1209.80 / 1235.09) 
(682.82 / 716.27) 
{[} 0.016 , 0.015 {]}}%
makecell{e)       
  « common
  bias » :       ( No $gamma$) ( $gamma$) 
·         
  5 Bias
  dependent : 
GCsp + (GCph + WL + XC)}&makecell{Not computable since z_cut < 0.9}&makecell{(781.09) (587.24) 
{[} 0.017 {]}}&makecell{(1565.86) (1254.87) 
{[} 0.009 {]}}%
end{tabular}

}

end{document}

Please follow this steps:

1. Cut and paste table to ms excel (I am using 2013).
2. Format some rows to make equal to the doc table, remove extra empty rows, etc.
3. Use addin excel2latex to generate the code of a LaTeX table. Insert the code in a LaTeX document with some added packages.
4. Make small changes: replace midrule  by hhline + change font size to fit the table in the page.

This is the resulting code

    documentclass[a4paper,10pt]{article} 

    usepackage{colortbl} 
    usepackage{multirow} 
    usepackage{hhline}
    setlengtharrayrulewidth{0.3pt}arrayrulecolor{black}

    usepackage[margin=.2in]{geometry}

    begin{document}
        
    % Table generated by Excel2LaTeX from sheet 'Sheet1'
    begin{table}[htbp]
            footnotesize  %% added
        centering
        caption{Add caption}
    %   begin{tabular}{|p{18.215em}|r|p{16.215em}|r|}
        begin{tabular}{|p{18.215em}|r|p{15.785em}|p{15.785em}|} % changed
    %%      midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}textbf{General Output Format :  (a/b) (c/d) [e,f]}} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}1) First couple of values : Without ?    (a / b)} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}textbf{2)Second couple of values : With ?                         (c / d)  }} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}textbf{3) Inside each couple of values : (a1 / b1) = (FoM(10 bins ) / FoM(11bins))}} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}textbf{4) Inside a couple of values  for GCsp: (a2 / b2) = FoM(4 bins) /FoM(5 bins)}} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{3}{p{50.5em}|}{cellcolor[rgb]{ .706,  .776,  .906}textbf{5) Standard deviation for each ? case (within brackets) : σ on (c,d)  ? cases [e, f] = [σc, σd]}} 
            hhline{~---}     rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}textcolor[rgb]{ 1,  0,  0}{textbf{Pessimistic (IST case):}}} & cellcolor[rgb]{ .706,  .776,  .906}textbf{Semi - Pessimistic:} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}textcolor[rgb]{ 1,  0,  0}{textbf{Optimistic (IST case):}}} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}kmax = 0.25 h.Mpc-1} & cellcolor[rgb]{ .706,  .776,  .906}kmax = 0.25 h.Mpc-1 & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}kmax = 0.3 h.Mpc-1} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(WL) = 1500} & cellcolor[rgb]{ .706,  .776,  .906}lmax(WL) = 1500 & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(WL) = 5000} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(GCph) = 750} & cellcolor[rgb]{ .706,  .776,  .906}lmax(GCph) = 750 & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(GCph) = 3000} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(XC) = 750} & cellcolor[rgb]{ .706,  .776,  .906}lmax(XC) = 750 & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}lmax(XC) = 3000} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}sig_p, sig_v to estimate} & cellcolor[rgb]{ .706,  .776,  .906}sig_p, sig_v to estimate & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}sig_p, sig_v fixed} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}Zcut for GCsp combined with GCph} & cellcolor[rgb]{ .706,  .776,  .906}No Zcut for GCsp combined with GCph & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ .706,  .776,  .906}No Zcut for GCsp combined with GCph} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}(14.18 / 13.81) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(56.14 / 52.61)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp - No ?  (4/5 bias) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(14.18 / 13.81)} & cellcolor[rgb]{ 1,  1,  1}(7.39 / 6.84) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (37.73 / 34.48)} 
            rowcolor[rgb]{ .706,  .776,  .906}             GCsp - ? (4/5 bias)  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(7.39 / 6.84)} & cellcolor[rgb]{ 1,  1,  1}[ 0.182 , 0.181 ] & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.136 , 0.133 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.182 , 0.181]} & multicolumn{1}{r|}{cellcolor[rgb]{ 1,  1,  1}} & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|c|}{} & multicolumn{1}{p{15.785em}|}{textbf{Pessimistic:}} & textbf{Semi- Pessimistic case =} & multicolumn{1}{p{15.785em}|}{textcolor[rgb]{ 1,  0,  0}{textbf{Optimistic (IST case):}}} 
            rowcolor[rgb]{ 1,  .706,  .953} textbf{Number of photo bias :} & multicolumn{1}{p{15.785em}|}{textbf{(10) / Extended (11)}} & textcolor[rgb]{ 1,  0,  0}{textbf{Pessimistic (IST case):}} & multicolumn{1}{p{15.785em}|}{textbf{(10) / Extended (11)}} 
            rowcolor[rgb]{ 1,  .706,  .953} textbf{(No spectro bias here)} & multicolumn{1}{p{15.785em}|}{textbf{Zcut < 0.9}} & textbf{(10) / Extended (11)} & multicolumn{1}{p{15.785em}|}{textbf{No-Zcut}} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|c|}{} &       & textbf{No-Zcut} &  
    %       midrule
        hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & cellcolor[rgb]{ 1,  1,  1} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(61.80 / 66.55)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCph  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(1.69 / 1.69)} & cellcolor[rgb]{ 1,  1,  1}(4.25 / 4.93) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (55.08 / 59.48)} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (1.10 / 1.10)} & cellcolor[rgb]{ 1,  1,  1} (3.15 / 3.78) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.129 , 0.128 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.466 , 0.466 ]} & cellcolor[rgb]{ 1,  1,  1}[ 0.429 , 0.409 ] & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} WL    & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}(24.09 / 25.72) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(46.82 / 50.65)} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(24.09 / 25.72)} & cellcolor[rgb]{ 1,  1,  1}(7.13 / 8.01) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(13.97 / 15.61)} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(7.13 / 8.01)} & cellcolor[rgb]{ 1,  1,  1}[ 0.191 , 0.180 ] & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.09 , 0.08 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.191 , 0.180 ]} & multicolumn{1}{r|}{cellcolor[rgb]{ 1,  1,  1}} & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & cellcolor[rgb]{ 1,  1,  1} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(1006.13 / 1035.82)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCph + WL + XC & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(211.52 / 213.50) } & cellcolor[rgb]{ 1,  1,  1}(358.41 / 382.86) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(441.97 / 477.52)} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|c|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(75.70 / 77.80)} & cellcolor[rgb]{ 1,  1,  1} (128.96 / 142.14) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.021 , 0.020 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.079 , 0.077 ]} & cellcolor[rgb]{ 1,  1,  1}[ 0.062 , 0.058 ] & cellcolor[rgb]{ 1,  1,  1} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & cellcolor[rgb]{ 1,  1,  1} & multicolumn{1}{r|}{cellcolor[rgb]{ 1,  1,  1}} & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|c|}{} &       & multicolumn{1}{r|}{} &  
            rowcolor[rgb]{ 1,  .706,  .953} textbf{Synthesis with simple sum (GCsp+GCph+WL) and } & multicolumn{1}{p{15.785em}|}{textbf{Pessimistic (IST case):  zcut (5 first bias for GCph) Zcut < 0.9}} & textbf{Semi-Pessimistic case:} & multicolumn{1}{p{15.785em}|}{textcolor[rgb]{ 1,  0,  0}{textbf{Optimistic (IST case):}}} 
            rowcolor[rgb]{ 1,  .706,  .953} textbf{GCsp+ (GCph+WL+XC)} &       & textbf{(10) / Extended (11)} & multicolumn{1}{p{15.785em}|}{(10) / Extended (11)} 
            rowcolor[rgb]{ 1,  .706,  .953} multicolumn{1}{|c|}{} &       & textbf{No-Zcut} & multicolumn{1}{p{15.785em}|}{textbf{No-Zcut}} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} a)        Specifications IST : & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}       (121.73 / 125.30)} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (351.18 / 367.42) } 
            rowcolor[rgb]{ .706,  .776,  .906} ·          (4 bias spectro) :  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (99.81 / 102.38)} & cellcolor[rgb]{ 1,  1,  1}(151.05 / 156.16) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(262.88 /279.53)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp + GCph + WL   & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}  [ 0.036, 0.035 ] } & cellcolor[rgb]{ 1,  1,  1}(119.72 /127.41) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.018 , 0.017 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}[ 0.035 , 0.035 ] & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} b)         Specifications IST : & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}      (384.80 / 386.64)} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(1220.39 / 1249.97) } 
            rowcolor[rgb]{ .706,  .776,  .906} ·          (4 bias spectro) :  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (255.84 / 257.64 ) } & cellcolor[rgb]{ 1,  1,  1}(550.01 / 573.48) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(692.62 /725.96)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp + (GCph + WL + XC)   & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.031, 0.031 ]} & cellcolor[rgb]{ 1,  1,  1}(320.07 / 333.93) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.016 , 0.015 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} multicolumn{1}{|r|}{} & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}[ 0.029 , 0.028 ] & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} c)        New specifications & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(119.67 / 123.34)} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(340.83 / 357.19)} 
            rowcolor[rgb]{ .706,  .776,  .906} ·          Bias independent : & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (99.20 / 101.84 )} & cellcolor[rgb]{ 1,  1,  1}(146.68 / 154.12) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(255.68 / 272.10)} 
            rowcolor[rgb]{ .706,  .776,  .906} (5 bias spectro) :  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.035, 0.035 ]} & cellcolor[rgb]{ 1,  1,  1}(119.72 / 125.45) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.018 , 0.017 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp + GCph + WL   & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}[ 0.035 , 0.035 ] & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} d)        New specifications & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(389.00 / 386.80)} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & cellcolor[rgb]{ 1,  1,  1} 
            rowcolor[rgb]{ .706,  .776,  .906} ·          Bias independent : & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1} (259.32 / 261.08)} & cellcolor[rgb]{ 1,  1,  1}(548.22 / 571.35) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(1209.80 / 1235.09)} 
            rowcolor[rgb]{ .706,  .776,  .906} (5 bias spectro) :  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.031, 0.030 ]} & cellcolor[rgb]{ 1,  1,  1}(320.84 / 334.05) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(682.82 / 716.27)} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp + (GCph + WL + XC) & cellcolor[rgb]{ 1,  1,  1} & cellcolor[rgb]{ 1,  1,  1}[ 0.029 , 0.028 ] & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.016 , 0.015 ]} 
    %       midrule
    hhline{~---}  %replace midrule
            rowcolor[rgb]{ .706,  .776,  .906} e)        « common bias » :       ( No ?) ( ?)  & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}textcolor[rgb]{ 1,  0,  0}{textbf{Not computable since z_cut < 0.9}}} & multicolumn{1}{c|}{cellcolor[rgb]{ 1,  1,  1}} & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}(1565.86) (1254.87)} 
            rowcolor[rgb]{ .706,  .776,  .906} ·          5 Bias dependent : & cellcolor[rgb]{ 1,  1,  1}textcolor[rgb]{ 1,  0,  0}{} & cellcolor[rgb]{ 1,  1,  1}(781.09) (587.24) & multicolumn{1}{p{15.785em}|}{cellcolor[rgb]{ 1,  1,  1}[ 0.009 ]} 
            rowcolor[rgb]{ .706,  .776,  .906} GCsp + (GCph + WL + XC) & cellcolor[rgb]{ 1,  1,  1}textcolor[rgb]{ 1,  0,  0}{} & cellcolor[rgb]{ 1,  1,  1}[ 0.017 ] & cellcolor[rgb]{ 1,  1,  1} 
    %       midrule
    hhline{~---}  %replace midrule
        end{tabular}%
        label{tab:addlabel}%
    end{table}%

    end{document}

While the solution might answer the question (going from word to editable LaTex code) the final result, as it is, is far from satisfactory,  mostly because the white lines that appear in the multirow colored cells. This is a known problem. See Colored tables and cline/hhline

Perhaps the result would be better if only the color is used to differentiate the cells.

Well, this might be so simple a solution that you've already thought of it.

In this answer I'll present several options:

1. As close to the original as possible (colors retained, but code messier)

In order to get as close to the original as possible, I would recommend using the following solution:

1. Install LibreOffice and save Table_Synthesis_for_SO.docx to Table_Synthesis_for_SO.odt.
2. Then go ahead and install Writer2LaTeX from extensions.libreoffice.org.
3. Export your document using the following settings (you can and probably should change US ASCII to UTF-8):
4. This will create the following document:

% This file was converted to LaTeX by Writer2LaTeX ver. 1.6.1
% see http://writer2latex.sourceforge.net for more info
documentclass[a4paper,12pt]{article}
usepackage[ascii]{inputenc}
usepackage[noenc]{tipa}
usepackage{tipx}
usepackage[geometry,weather,misc,clock]{ifsym}
usepackage{pifont}
usepackage{eurosym}
usepackage{amsmath}
usepackage{wasysym}
usepackage{amssymb,amsfonts,textcomp}
usepackage[T3,T1]{fontenc}
usepackage[varg]{txfonts}usepackage[english,french]{babel}
usepackage{color}
usepackage{fancyhdr}
usepackage[top=2.501cm,bottom=1cm,left=2.501cm,right=2.501cm,nohead,nofoot]{geometry}
usepackage{array}
usepackage{supertabular}
usepackage{hhline}
usepackage{colortbl}
usepackage{hyperref}
hypersetup{pdftex, colorlinks=true, linkcolor=blue, citecolor=blue, filecolor=blue, urlcolor=blue, pdftitle=}
providecommandtextsubscript[1]{ensuremath{{}_{text{#1}}}}
makeatletter
newcommandarraybslash{let@arraycr}
makeatother
raggedbottom
% Paragraph styles
renewcommandfamilydefault{rmdefault}
newenvironment{stylePxxxiv}{clearpagesetcounter{page}{1}pagestyle{Standard}
setlengthleftskip{0cm}setlengthrightskip{0cm plus 1fil}setlengthparindent{0cm}setlengthparfillskip{0pt plus 1fil}setlengthparskip{0cm plus 1pt}writerlistparindentwriterlistleftskipselectlanguage{english}leavevmodenormalfontnormalsizenormalcolorwriterlistlabelignorespaces}{unskipvspace{0cm plus 1pt}par}
% Footnote rule
setlength{skipfootins}{0.119cm}
renewcommandfootnoterule{vspace*{-0.018cm}setlengthleftskip{0pt}setlengthrightskip{0pt plus 1fil}noindenttextcolor{black}{rule{0.25columnwidth}{0.018cm}}vspace*{0.101cm}}
% Pages styles
fancypagestyle{Standard}{fancyhf{}
  fancyhead[L]{}
  fancyfoot[L]{}
  renewcommandheadrulewidth{0pt}
  renewcommandfootrulewidth{0pt}
  renewcommandthepage{arabic{page}}
}
pagestyle{Standard}
setlengthtabcolsep{1mm}
renewcommandarraystretch{1.3}
% List styles
newcommandwriterlistleftskip{}
newcommandwriterlistparindent{}
newcommandwriterlistlabel{}
newcommandwriterlistremovelabel{aftergroupletaftergroupwriterlistparindentaftergrouprelaxaftergroupletaftergroupwriterlistlabelaftergrouprelax}
newcommandliststyleWWNumv{%
renewcommandtheenumi{alph{enumi}}
renewcommandtheenumii{alph{enumi}.alph{enumii}}
renewcommandtheenumiii{alph{enumii}.roman{enumiii}}
renewcommandtheenumiv{roman{enumiii}.arabic{enumiv}}
renewcommandlabelenumi{theenumi}
renewcommandlabelenumii{theenumii}
renewcommandlabelenumiii{theenumiii}
renewcommandlabelenumiv{theenumiv}
}
newcommandliststyleWWNumvi{%
renewcommandlabelitemi{[F0B7?]}
renewcommandlabelitemii{o}
renewcommandlabelitemiii{[F0A7?]}
renewcommandlabelitemiv{[F0B7?]}
}
sloppy
title{}
begin{document}
begin{stylePxxxiv}
                
end{stylePxxxiv}
begin{center}
begin{minipage}{0.041cm}
begin{center}
tablefirsthead{}
tablehead{}
tabletail{}
tablelasttail{}
begin{supertabular}{|m{3.307cm}|m{2.915cm}|m{2.9659998cm}|m{2.97cm}|}
hline
cellcolor[rgb]{1.0,0.7058824,0.9529412}~
 &
multicolumn{3}{m{9.251cm}|}{cellcolor[rgb]{0.7058824,0.7764706,0.90588236}~

{selectlanguage{english}fontsize{7.5pt}{9.0pt}selectfontbfseriescolor{black} General Output Format :  (a/b) (c/d) [e,f]}

~

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{1) First couple of values : Without }}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{[D835?][DEFE?]}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{ }}} ${equiv}$ foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ (a / b) }}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{2)Second couple of values : With }}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{[D835?][DEFE?]}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ }}}} ${equiv}$ foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ (c / d)  }}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{3) Inside each couple of values : (a1 / b1) = (FoM(10 bins ) / FoM(11bins))}}}}}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} 4) Inside a couple of values  for GCsp: (a2 / b2) = FoM(4 bins) /FoM(5 bins)}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{5) Standard deviation for each }}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{[D835?][DEFE?]}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ case~(within brackets) : }}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{$sigma $}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ on (c,d)  }}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{[D835?][DEFE?]}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{ cases [e, f] = [}}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{$sigma $}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{textsubscript{c, }}}}}{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{$sigma $}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{textsubscript{d}}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{]}}}}}

~
}hline
 &
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Pessimistic (IST case):par}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{k}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max }}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{= 0.25 h.Mpc}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsuperscript{{}-1}}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(WL) = 1500}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(GCph) = 750}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(XC) = 750}}}}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} sig_p, sig_v to estimate}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} Zcut for GCsp combined with GCph} &
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}{fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Semi - Pessimistic:}

{color{black} {fontsize{8pt}{9.6pt}selectfont textcolor{black}{k}}{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max }}}{fontsize{8pt}{9.6pt}selectfont textcolor{black}{= 0.25 h.Mpc}}{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsuperscript{{}-1}}}}

{color{black} {fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(WL) = 1500}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(GCph) = 750}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(XC) = 750}}}}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} sig_p, sig_v to estimate}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} No Zcut for GCsp combined with GCph} &
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Optimistic (IST case):}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{k}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max }}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{= 0.3 h.Mpc}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsuperscript{{}-1}}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(WL) = 5000}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(GCph) = 3000}}}}

{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{l}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{textsubscript{max}}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(XC) = 3000}}}}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} sig_p, sig_v fixed}

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} No Zcut for GCsp combined with GCph}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}~

{centeringcolor{black} foreignlanguage{english}{{fontsize{7.5pt}{9.0pt}selectfont textcolor{black}{GCsp - No }}}foreignlanguage{english}{{fontsize{7.5pt}{9.0pt}selectfont textit{textcolor{black}{$gamma $}}}}foreignlanguage{english}{{fontsize{7.5pt}{9.0pt}selectfont textcolor{black}{  (4/5 bias)}}}par}

{color{black} foreignlanguage{english}{{fontsize{7.5pt}{9.0pt}selectfont textcolor{black}{ GCsp - }}}{fontsize{7.5pt}{9.0pt}selectfont textcolor{black}{[D835?][DEFE?]}}foreignlanguage{english}{{fontsize{7.5pt}{9.0pt}selectfont textcolor{black}{ (4/5 bias) }}}}

~
 &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (14.18 / 13.81)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (7.39 / 6.84)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.182 , 0.181]par}

~
 &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (14.18 / 13.81)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (7.39 / 6.84)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.182 , 0.181 ]} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (56.14 / 52.61)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (37.73 / 34.48)par}

centeringarraybslash{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.136 , 0.133 ]}}}}hline
cellcolor[rgb]{1.0,0.7058824,0.9529412}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Number of photo bias :par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} (No spectro bias here)par}

~
 &
cellcolor[rgb]{1.0,0.7058824,0.9529412}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Pessimistic:par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} (10) / Extended (11)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Zcut {textless} 0.9} &
cellcolor[rgb]{1.0,0.7058824,0.9529412}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Semi- Pessimistic case =par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Pessimistic (IST case):par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} (10) / Extended (11)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} No-Zcut} &
cellcolor[rgb]{1.0,0.7058824,0.9529412}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Optimistic (IST case):par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} (10) / Extended (11)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} No-Zcut}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCphpar}

~
 &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (1.69 / 1.69)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (1.10 / 1.10)par}

{centeringcolor{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.466 , 0.466 ]}}}par}

~
 &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (4.25 / 4.93)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (3.15 / 3.78)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.429 , 0.409 ]} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (61.80 / 66.55)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (55.08 / 59.48)par}

centeringarraybslash{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.129 , 0.128 ]}}}}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} WL} &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (24.09 / 25.72)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (7.13 / 8.01)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.191 , 0.180 ]par}

~
 &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (24.09 / 25.72)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (7.13 / 8.01)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.191 , 0.180 ]} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (46.82 / 50.65)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (13.97 / 15.61)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.09 , 0.08 ]}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} GCph + WL + XCpar}

~
 &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (211.52 / 213.50) par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (75.70 / 77.80)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.079 , 0.077 ]par}

~
 &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (358.41 / 382.86)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (128.96 / 142.14)par}

centering{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.062 , 0.058 ]}}}} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (1006.13 / 1035.82)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (441.97 / 477.52)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.021 , 0.020 ]}hline
cellcolor[rgb]{1.0,0.7058824,0.9529412}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Synthesis with simple sum (GCsp+GCph+WL) and par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} GCsp+ (GCph+WL+XC)par}

~
 &
cellcolor[rgb]{1.0,0.7058824,0.9529412}~

centering{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{red}{Pessimistic (IST case):  }}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{zcut (5 first bias for GCph) Zcut {textless} 0.9}}}}} &
cellcolor[rgb]{1.0,0.7058824,0.9529412}~

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} Semi-Pessimistic case:}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} (10) / Extended (11)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} No-Zcut} &
cellcolor[rgb]{1.0,0.7058824,0.9529412}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Optimistic (IST case):par}

{centeringcolor{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{(}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textbf{textcolor{black}{10) / Extended (11)}}}}par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{black} No-Zcut}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}liststyleWWNumv
begin{enumerate}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} Specifications IST :}
end{enumerate}
liststyleWWNumvi
begin{itemize}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (4 bias spectro) : }
end{itemize}
{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCsp + GCph + WL  } &
cellcolor{white}{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (121.73 / 125.30)}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (99.81 / 102.38)par}

centering{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{ [}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.036, 0.035 ] }}}} &
cellcolor{white}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (151.05 / 156.16)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (119.72 /127.41)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.035 , 0.035 ]par}

~
 &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (351.18 / 367.42) par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (262.88 /279.53)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.018 , 0.017 ]}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}liststyleWWNumv
begin{enumerate}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  Specifications IST :}
end{enumerate}
liststyleWWNumvi
begin{itemize}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (4 bias spectro) : }
end{itemize}
{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCsp + (GCph + WL + XC)  } &
cellcolor{white}{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (384.80 / 386.64)}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (255.84 / 257.64 ) par}

centering{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.031, 0.031 ]}}}} &
cellcolor{white}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (550.01 / 573.48)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (320.07 / 333.93)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.029 , 0.028 ]par}

~
 &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (1220.39 / 1249.97) par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (692.62 /725.96)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.016 , 0.015 ]}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}liststyleWWNumv
begin{enumerate}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} New specifications}
end{enumerate}
liststyleWWNumvi
begin{itemize}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} Bias independent :}
end{itemize}
{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (5 bias spectro) : }

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCsp + GCph + WL  } &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (119.67 / 123.34)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (99.20 / 101.84 )par}

centering{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} {fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.035, }}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.035 ]}}}} &
cellcolor{white}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (146.68 / 154.12)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (119.72 / 125.45)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.035 , 0.035 ]par}

~
 &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (340.83 / 357.19)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (255.68 / 272.10)par}

centeringarraybslash{color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.018 , 0.017 ]}}}}hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}liststyleWWNumv
begin{enumerate}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} New specifications}
end{enumerate}
liststyleWWNumvi
begin{itemize}
item {selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} Bias independent :}
end{itemize}
{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (5 bias spectro) : }

{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCsp + (GCph + WL + XC)} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (389.00 / 386.80)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black}  (259.32 / 261.08)par}

centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.031, 0.030 ]} &
cellcolor{white}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (548.22 / 571.35)par}

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (320.84 / 334.05)par}

centering{fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.029 , 0.028 ]} &
cellcolor{white}~

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (1209.80 / 1235.09)par}

{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (682.82 / 716.27)par}

{centeringcolor{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{[}}} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{0.016 , 0.015 ]}}}par}

~
hline
cellcolor[rgb]{0.7058824,0.7764706,0.90588236}liststyleWWNumv
begin{enumerate}
item {color{black} foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{{guillemotleft}~common bias~{guillemotright} :  ( }}}foreignlanguage{english}{{fontsize{9pt}{10.8pt}selectfont textcolor{black}{No }}}{fontsize{9pt}{10.8pt}selectfont textcolor{black}{[D835?][DEFE?]}}foreignlanguage{english}{{fontsize{9pt}{10.8pt}selectfont textcolor{black}{) ( }}}{fontsize{9pt}{10.8pt}selectfont textcolor{black}{[D835?][DEFE?]}}foreignlanguage{english}{{fontsize{9pt}{10.8pt}selectfont textcolor{black}{)}}}foreignlanguage{english}{{fontsize{8pt}{9.6pt}selectfont textcolor{black}{ }}}}
end{enumerate}
liststyleWWNumvi
begin{itemize}
item {fontsize{8pt}{9.6pt}selectfontcolor{black} 5 Bias dependent :}
end{itemize}
{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} GCsp + (GCph + WL + XC)} &
cellcolor{white}centering{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontbfseriescolor{red} Not computable since z_cut {textless} 0.9} &
cellcolor{white}~

{centeringfontsize{8pt}{9.6pt}selectfontcolor{black} (781.09) (587.24)par}

centering{fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.017 ]} &
cellcolor{white}{centeringselectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} (1565.86) (1254.87)par}

centeringarraybslash{selectlanguage{english}fontsize{8pt}{9.6pt}selectfontcolor{black} [ 0.009 ]}hline
end{supertabular}
end{center}
end{minipage}
end{center}
end{document}

I would strongly recommend removing or at least commenting the following lines:

%begin{center}
%begin{minipage}{0.041cm}
%begin{center}
…
%end{center}
%end{minipage}
%end{center}

This will vastly improve the output and give you something like this:

2. Further away from the original (colors lost, but code quite readable)

This is what I would recommend to you. It gives you an excellent base for your own alterations, preserves the table and is actually quite clean codewise.

Here are the necessary settings for Writer2LaTeX:

With all the code samples I'm close to the max. word count available, so I'll have to call it quits here.

Final remarks

I think, LibreOffice can really help you here, since it produces an actual table. I have also tried pandoc which would produce empty tex and pdf files.

My recommendation: Use the Ultra-clean Article and start building from there. If you have trouble guessing the colors or which packages to load, have a look at solution 1 above and use the necessary code from there. The Ultra-clean Article loads less packages, removes all the unnecessary fontsize declarations from Word/LibreOffice and gives you a really nice document.

Just remember to remove the center and minipage environments and you'll be fine.

I hope this helps.

Edit: Considered is @youpilat13 comment.

It might be worth to rewrite your table in LaTeX from scratch. For example first few rows can be formatted as follows:

documentclass{article}
usepackage[a4paper,
            margin=.2in]{geometry}
usepackage[T1]{fontenc}
usepackage[frenchb]{babel}

usepackage[table]{xcolor}
usepackage{hhline,
            multirow,
            tabularx}               % new

newcolumntype{L}{>{raggedrightarraybackslash}X}
usepackage{linegoal}               % new

setlengtharrayrulewidth{0.6pt}arrayrulecolor{black}
usepackage{amsmath, amssymb}
usepackage{enumitem}               % new
%---------------- show page layout. don't use in a real document!
usepackage{showframe}
renewcommandShowFrameLinethickness{0.15pt}
renewcommand*ShowFrameColor{color{red}}
%---------------------------------------------------------------%

begin{document}
    begin{table}[htbp]
caption{Add caption}
label{tab:addlabel}
    centering
    footnotesize
    setlengthextrarowheight{2pt}
    setlengthtabcolsep{3pt}
begin{tabularx}{linewidth}{|>{columncolor[rgb]{.682, .667, .667}bfseries}L|
                             *{3}{L|} }
    hhline{~|---|}
    rowcolor[rgb]{.682, .667, .667}
multicolumn{1}{X|}{cellcolor{white}}
    &   multicolumn{3}{p{dimexpr3hsize/4-2tabcolsep-2arrayrulewidth}|}%%
        {bfseries
         General Output Format:  (a / b) (c / d) [e, f]
         begin{enumerate}[nosep,
                          leftmargin=*,
                          label=textbullet,
                          before=vspace{1ex},
                          after=vspace{-1ex},
                          ]
        item   First couple of values: Without $gamma$: (a / b)
        item   Second couple of values: With $gamma$: (c / d)
        item   Inside each couple of values: (a1/b1) = (FoM(10 bins) / FoM(11bins))
        item   Inside a couple of values  for GCsp: (a2 / b2) = FoM(4 bins) / FoM(5 bins)
        item   Standard deviation for each $gamma$ case (within brackets): $sigma$ on (c,d)  $gamma$ cases [e, f] = [$sigma_{mathrm{c}}, sigma_{mathrm{d}}$]
        end{enumerate}
        }
        hhline{~|---|}
    rowcolor[rgb]{ .816, .808, .808}
multicolumn{1}{X|}{cellcolor{white}}
    &   textcolor[rgb]{ .267, .447, .769}{textbf{Pessimistic (IST case):}}newline
        $k_{max} = 0.25,text{h.Mpc}-1$newline
        $l_{max}(WL) = 1500$newline
        $l_{max}(GCph) = 750$newline
        $l_{max}(XC) = 750$newline
        $sigma_{mathrm{p}}, sigma_{mathrm{v}}$ to estimate $Z_{mathrm{cut}}$ for GCsp combined with GCph
        &   textbf{Semi - Pessimistic:}newline
            $k_{max} = 0.25,text{h.Mpc}-1$newline
            $l_{max}(WL) = 1500$newline
            $l_{max}(GCph) = 750$newline
            $l_{max}(XC) = 750$newline
            $sigma_{mathrm{p}}, sigma_{mathrm{v}}$ to estimate No-$Z_{mathrm{cut}}$ for GCsp combined with GCph
            &   textcolor[rgb]{.267, .447, .769}{textbf{Optimistic (IST case):}}newline
                $k_{max} = 0.3,text{h.Mpc}-1$newline
                $l_{max}(WL) = 1500$newline
                $l_{max}(GCph) = 3000$newline
                $l_{max}(XC) = 3000$newline
                $sigma_{mathrm{p}}, sigma_{mathrm{v}}$ fixed Non-$Z_{mathrm{cut}}$ for GCsp combined with GCph
     hhline{|----|}
GCsp - No $gamma$  (4/5 bias)
        &   (14.18 / 13.81)
            &   (14.18 / 13.81)
                &   (56.14 / 52.61)
     hhline{|----|}
multirow{2}{=}{GCsp - $gamma$ (4/5 bias)}
    &   (7.39 / 6.84)newline
        [ 0.182, 0.181]
        &   (7.39 / 6.84)newline
            [ 0.182, 0.181 ]
            &   (37.73 / 34.48)newline
                [ 0.136 , 0.133 ]
     hhline{|----|}

rowcolor[rgb]{ .816,  .808,  .808}
Pessimistic:
    &   textbf{Semi- Pessimistic case}
        &   textcolor[rgb]{.267, .447, .769}{textbf{(Optimistic IST case):}}
            &   textcolor[rgb]{.267, .447, .769}{textbf{Pessimistic (IST case):}}
    
        rowcolor[rgb]{.816, .808, .808}
Number of photo bias:
    &   textbf{(10) / Extended (11)}
        &   textbf{(10) / Extended (11)}
            &   textbf{(10) / Extended (11)}
    
        rowcolor[rgb]{.816, .808, .808}
(No spectro bias here), $textbf{No-Z}_{textbf{cut}}$
    &   $mathbf{Z}_{mathbf{cut}} < 0.9$
        &   textbf{(10) / Extended (11)}
            &   textbf{No-Z}$_{textbf{cut}}$
    
        rowcolor[rgb]{ .816,  .808,  .808}
        hhline{|----|}
end{tabularx}%
    end{table}%
end{document}

which gives:

I'm sorry but temporary imgur doesn't work :-(

(red lines indicate text border)

As you can see, the table code is quite shorter and clear. It has no clutter with multcolumn cells, coloring individual cells etc.