If we keep "can" here, then I think the parenthetical needs to say "is", not "were".

Alternatively, could we say "would be able to produce"?

I'm happy with either. I'm a little worried that ISO will decide to declare "would" as verboten next (the upcoming revised Directives disallow use of any verbal forms not explicitly permitted, which would disallow "would"). But we can face that if and when it happens.

fixed to "is"

We need to be able to talk about hypotheticals in proper English phrasing, that includes "could" and "were" and "would" and "might". Everything else is just stupid.
(I agree with some of the -> can changes we have been doing; they seem to be clear improvements occasionally.)

I'm not sure "would" works here. Second options? @zygoloid?

We have a bunch of max-munch rules that all follow the same pattern.

OK, then maybe this is fine as is (likewise below).

What I've been suggesting in other PRs is:
"longest sequence of characters that matches the syntax of a preprocessing-token"
... which seems more precise than our prior wording in the various tentative parsing areas, and distinguishes between matching the syntax of X and actually forming a valid X, without getting into hypotheticals.

fixed