Adding Spacemacs documented layers fails

Adding layers existing in the layer section of the .spacemacs documentation results in failed test in the dot-test-results buffer generated after reloading the .spacemacs file (with SPC-f-e-R).

increminated layers were :
neotree ;; for filetree

notmuch ;; for emails

parinfer ;; clojure / lisp paren inference

pdf ;; pdf visualisation

prettier

The * spacemacs* welcome screens gets some warnings but couldn’t find any other error messages to help debug :

   Warnings:
           - Unknown layer neotree declared in dotfile.      
           - Unknown layer notmuch declared in dotfile.      
           - Unknown layer parinfer declared in dotfile.      
           - Unknown layer pdf declared in dotfile.      
           - Unknown layer prettier declared in dotfile.      
           - package twittering-mode not initialized in layer keyboard-layout, you 
             may consider removing this package from the package list or use the :toggle 
             keyword instead of a `when' form.      
           - package linum not initialized in layer nlinum, you may consider removing 
             this package from the package list or use the :toggle keyword instead of a `when' form.      
           - package linum-relative not initialized in layer nlinum, you may consider
             removing this package from the package list or use the :toggle keyword 
             instead of a `when' form.      
           - More than one init function found for package helm-make. Previous owner was ivy,
             replacing it with layer helm.      
           - More than one init function found for package smex. Previous owner was ivy,
             replacing it with layer smex.      
           - package evil-nerd-commenter not initialized in layer evil-commentary, you may
             consider removing this package from the package list or use the :toggle keyword
             instead of a `when' form.      
           - package vi-tilde-fringe not initialized in layer vim-empty-lines, you may
             consider removing this package from the package list or use the :toggle keyword
             instead of a `when' form.      
           - tern binary not found!     

my config :
OS: mac osX Catalina 10.15.5
emacs : GNU Emacs 26.3 (build 1, x86_64-apple-darwin18.5.0, Carbon Version 158 AppKit 1671.4)
fetch with brew install emacs-plus@26 IIRW

spacemacs à jour (latest)
271 packages loaded in 18.794s (e:202 r:2 l:18 b:49)

(this seems slow, may be because of spaceline-all-the-icons)

My .spacemacs is still a work in progress and thus not in a github repo yet so I attached a gist link below.

Thanks for any hits on how to get thos layers working.

Best
Samusz

.spacemacs file: https://gist.github.com/samusz/2cfb1ced064276be06eee4488cc86788