In q10 of the OG, note that two options use which. Both the options make crucial tense errors.
Similarly, in Q92 of the Verbal Review (second edition), three options use which with a restrictive clause. Those options contain crucial errors (missing a definite article, using cycles to refer to the life cycle of a single parasite, ambiguous pronoun references). The explanation doesn't call out the use of which with a restrictive clause. If it had been an important distinction, they would have mentioned it.
It's possible that the explanations aren't written by the same team that framed the questions. But even so, the inclusion of which without the comma in three of the five options suggests (to me, anyway) that the GMAT doesn't seem to consider the distinction important. I am fairly certain that the GMAT won't make this the primary error in any question.
If it does do that, then we are in trouble.
GMAT and MBA admissions Coach