Meaning of "so that"

In The Comprehensive Grammar of the English Language, "so that" is considered to be a subordinating conjunction, otherwise called a subordinator.

14.11 p. 998 Subordinators
SUBORDINATORS (or more fully SUBORDINATING CONJUNCTIONS) are the most important formal device of subordination, particularly for finite clauses. Like prepositions, which they resemble in having a relating function, subordinators forming the core of the class consist of a single word, but there is a larger range of complex subordinators which function, to varying degrees, like a single conjunction.
[…]

14.12 […]
SIMPLE SUBORDINATORS
after, although, as, because, before, directly (informal, esp BrE), if, immediately (informal, esp BrE), lest (esp AmE), like (informal, esp AmE), once, since, that, though
[…]

COMPLEX SUBORDINATORS
ending with that:
        but that, in that, in order that, insofar that (formal, rare), in the event that, save that (literary), such that
ending with optional that:
(a) participle form:         [assuming, considering, excepting, given, granted,granting, provided, providing, seeing, supposing ] (that)
(b) others:
        [except, for all, now, so] (that)

14.13
CORRELATIVE SUBORDINATORS
(a) as … so
(b) as … as
      so … as
      such… as
      so … (that)
      such …(that)
[…]

15.20 p. 1070

Adjuncts and disjuncts 15.20 Adjuncts and disjuncts tend to differ semantically in that adjuncts denote circumstances of the situation in the matrix clause, whereas disjuncts comment on the style or form of what is said in the matrix clause (style disjuncts) or on its content (content or attitutlinal disjuncts). The primary difference is that they differ syntactically in that disjuncts are peripheral to the clause to which they are attached.
The syntactic difference does not manifest itself in differences in form or position. For example, finite clauses that function as adjuncts and disjuncts may share the same subordinator, and in both functions the clauses may be positioned initially or finally. The peripheral status of disjuncts is indicated mainly negatively: they do not allow a number of syntactic processes to apply to them that are allowed by adjuncts, processes that reflect a measure of integration within the superordinate clause. In this section we consider the differences between adjunct and disjunct clauses. Below we exemplify the contrasts between adjunct clauses in the [a] sentences and content disjunct clauses in the [b] sentences:
[…]
purpose so that [a] and result so that [b]:
♦ They took a plane so that they could get there early. [a]
♦ We know her well, so that we can speak to her on your behalf.[b]

Clauses of result
15.49
Clauses of result are introduced by the subordinators so that (formal) and so. These clauses overlap with those of purpose both in meaning and in subordinators. The chief semantic difference is that result clauses are factual rather than putative: both express result, but in the result clause the result is achieved, whereas in the purpose clause it is yet to be achieved - it is a desired or aimed-at result. Hence finite clauses of result do not require a modal auxiliary:
♦ We paid him immediately, so (that) he left contented. [result] [1]
♦ We paid him immediately so (that) he would leave contented. [purpose] [2]

Note[b] […] If so intensifies a verb it may appear at the end of the clause, and an intonation break (or in writing, a comma) is normal after so:
♦ They wanted it so, (that) they agreed to pay more than the normal price. [so = 'so much'] In formal style, so may be a manner adverb rather than an intensifier, in which case that must be retained:
♦ They so arranged the seating that all had a clear view of the stage. [so = 'in such a way'] (formal) Again, so may be postposed:
♦ They arranged the seating so, that all had a clear view of the stage. (formal)

Some minor changes are needed in the initial sentence

• Firstly, the Employer will make a demand on the bank which provided the PB. For tactical reasons, this demand is often made so, that the bank has as little time as possible to inform the Contractor, and at an inconvenient time, so that the Contractor struggles to engage lawyers to prevent the bank from paying out on the Performance Bond.

• (equivalent) Firstly, the Employer will make a demand on the bank which provided the PB. For tactical reasons, this demand is often so made, that the bank has as little time as possible to inform the Contractor, and at an inconvenient time, so that the Contractor struggles to engage lawyers to prevent the bank from paying out on the Performance Bond.

The first occurrence of "so that" is that of "so" as an adverb of manner and of the conjunction "that" which constitute a correlative subordinator introducing a result clause; "so" means "in such a manner". The second is that of the complex subordinator, and it introduces a result clause.

Firstly, the Employer will make a demand on the bank which provided the PB. For tactical reasons, this demand is often made [so that the bank has as little time as possible to inform the Contractor], and at an inconvenient time [so that the Contractor struggles to engage lawyers to prevent the bank from paying out on the Performance Bond].

Preliminary point: "so that" is not a syntactic unit, not a 'compound subordinator. The bracketed expressions are purpose adjuncts consisting of the preposition "so" followed by a declarative content clause as its complement.

Some older grammars claim that "so that" is a syntactic unit, a constituent, but this is wrong. It actually consists of the preposition "so" with a declarative content clause as its complement. We know this to be the case because the subordinator "that" is readily omissible.