I will edit for you, drawing from 12 years experience

Perhaps you just want professional eyes to go over something.

The late-stage work could be a simple proofreading! This involves checking the proofs of already-formatted material for minor, mechanical errors in the copy (meaning spelling mistakes, or small deviations from the style sheet). A clean-up, so to speak.

For a slightly more involved process, consider copyediting, which involves looking at grammar, diction, spelling, punctuation, and other mechanics of style; checking for consistency, etc. It can also include formatting of tables, figures, lists, and so on.

This would be in contrast to more involved stylistic guidance, which is along the lines of clarifying meaning, eliminating jargon, polishing language, and other line-by-line work. This is a much more collaborative process, with substantive suggestions and changes. A sort of "building" of the project together over time.