Yes, your sentence means what you want it to mean; the complaint is not just pedantic--it is outright mistaken. In my experience with English language conventions, "this" means "the criteria." The sentence further clarifies what that criteria is, i.e. "establishing, delineating, and reviewing..." I will show how this works by parsing the two parts of the sentence separately, and then comparing the parts.
The Employment Insurance (EI) Act doesn’t state the criteria for
establishing, delineating, and reviewing EI regional boundaries;
I'm not sure how to find a grammar book or website to prove this, nor do I have the proper grammar terms on the tip of my tongue. However, based on my extensive reading experience in the English language for instructions and other literature, I parse the above sentence thus:
Bare Subject: Employment Insurance (EI) Act
Bare Predicate: doesn't state
Object of Bare Predicate: criteria
Modifier of the Object of the Bare Predicate: the
Subject Complement for Bare Predicate "doesn't state": for establishing, delineating, and reviewing regional boundaries
My apologies; I'm sure I've got some terms wrong but I think my meaning is clear. I will use the same terms for the Second Part of this sentence.
it has delegated this responsibility to the CEIC and ESDC.
I parse it thus:
Bare Subject: it
Bare Predicate: has delegated
Object of Bare Predicate: responsibility
Modifier of the Object of the Bare Predicate: this
Subject Complement for Bare Predicate "has delegated": to the CEIC and ESDC
COMPARING THE PARTS
Because the second part of this sentence is separated from the first by only a semicolon, the two parts obviously refer to the same items. I will now pair up the items for easy comparison.
Bare Subject: 1 Employment Insurance (EI) Act; 2 it
Bare Predicates: 1 doesn't state; 2 has delegated
Objects of Bare Predicates: 1 criteria; 2 responsibility
Modifiers of the Objects of the Bare Predicates: 1 the; 2 this
The subject complements are probably not necessary for this part of the discussion; I am least confident about the terms regarding the parsing of those parts.
Employment Insurance (EI) Act = it
the criteria = this responsibility
It is not grammatically possible to divide up, or separate from each other, the three items listed under "responsibility," i.e. "this responsibility." "This" clearly means "the criteria for establishing, delineating, and reviewing EI regional boundaries."