Just came across a really cool Umineko reference in TRianThology!
【ウサギ】「かの大ベアトリーチェ卿のお言葉にもございますっ、曰くっ、宇宙は1人では作れないっ」
Episode 4 spoiler I think? My rough translation is “In the words of the great Beatrice, ‘A universe cannot be made by one person alone.’”
So yeeah, Beatrice mentioned by name as a character Alice and Usagi know of! Seems like the story of Umineko is a bit of a legend in TRianThology. And I’m pretty sure Alice is indeed calling herself a witch here.