After talking with some editors on the discord (I pinged all of them but only a few replied), we came to the conclusion that there was not enough evidence to decisively call FRSO revisionist or opportunist. I made a plan to reorder the page that was accepted:
I moved the uniform thing to an "activities" section (FRSO was right in this instance, I would have acted the same as them and so it's not really a controversy).
I renamed the controversy section to criticisms, as it's more faithful to what was actually being discussed. I kept the Brandon Johnson endorsement but noted FRSO's reasoning for it.
Finally, I removed all mentions of revisionism or opportunism as they could not be backed up.
I have to point out that while ProleWiki does not follow a "no POV" rule as strictly as Wikipedia does, there didn't seem to be any actual controversy regarding the two incidents. For a controversy to happen, it needs many people to call it out. In this case, we couldn't back it up with any notable outrage outside of our editorship here. When the claim comes from our editorship especially, it can make it seem like we are soapboxing.
When editing communist party pages, please remember to afford them good faith. While we should call out issues in parties, writing off a whole party as opportunist and revisionist based on two minor(ish) events is a very strong accusation that may turn potential editors away.