In the ghostipedia theres hints saying stuff about multiple kuppas and another one about the thunder girl talking about taking them to  some apartment room and getting the elder sister? I'm really stuck with this if anyone could help me with this and any other ghost animation secrets that'd be awesome

ThunderGirl animations will be added to the new map in the next update. I don’t know about Kupper, but when I read it, it became interesting.

Both are not in game yet. They will be added in future update.