I think that qvitter moderation is good on a base level, but it isn't as comprehensive as classic interface moderation which enables looking at members and deleting accounts should it be needed. Although I know that fl0wn had issues with the ability to delete accounts. There is probably more that I don't know in there.

Moderators/admins should probably have the ability to edit groups in case those violate the rules too. Just as posts can be deleted.

I don't actually know the extent of moderating with pleroma yet. I may just become defunct! :')