If this is about the Yandere Wiki, you could make a follow-up message to ProfessorTofty about the situation.

That was one of my reasons for bringing this up, given my opponent's behavior, but I don't have any interest in that wiki anymore. Not least because of the very negative experience I had with that user. I'm just curious about what other people think about other things in general. I was hoping to somehow influence the creation of rules that would avoid the abuse of adopting abandoned wikis to resolve personal content wars, but I simply don't know how common such situations are.

Those situations can often be solved with the mediation of Fandom support.

As someone who's active in discussions here, I would say they're not that common as posts asking for help don't often appear.

I can only think of one instance off the top of my head. Once the person who handled the adoption was made aware of the situation, they stripped the rights from the abuser.

I've been in similar situations about three times, one of which involved my opponent potentially working on getting a flag while both I and his (potential) main account were banned for edit wars. In all cases, I was told that while the staff does not support or condemn such actions, they have no control over them because I noticed it relatively late and they can't interfere with someone else's work on a project just because an admin behaved badly.

I can understand their decision in general (even though I am still shocked by such gross slander and manipulation from my opponent), but it does not save from similar situations in the future with me or other users who find themselves in some disputes in the middle of old wikis. For example, just a year or two ago I met a user who endlessly rewrote the same fragment of text in order to artificially achieve the required number of edits at a time when the original admin and I were absent from the project.