(Umineko Spoilers) Spoiler-tagging a topic title isn’t possible, at least at the moment. I did give this some thought when I created the first batch of topics. I’d say EVA can be discussed in Eva’s topic (which, uh, doesn’t exist yet). Spoilers regarding Ange, and also Will and Dlanor, can be prevented by having only their first name in the topic title. The Beatrices might have to share a topic though. I don’t think there’s a problem with having separate Tohya and Ikuko topics that refer to their true identities.
(More Spoilers) I have been wondering on how to best make a Yasu topic though. For now I thought of simply making the Beatrice topic the general Yasu topic (it makes a lot of sense) though Clair would work equally well. I guess there’s no real harm in having a literal Yasu topic either since the name doesn’t give anything away.