This is your opinion, to me there’s no way to reconcile that arc8 and arc4 has different branches of the same thing.
It’s like a mini-rokkenjima, and as far as I know I’m far from the only one who views it that way. Ange vanished after the skyscrapper event.
Did she commit suicide and just die?
Did she go on a trip like arc4 shows?
Or did she go on to become an author after changing her name?
Or maybe other possibilities, it’s a catbox after all.
It’s sorta like multiple arcs written from the same catbox, and I have no reason to doubt this is the case.
I would also point out that I think the most trustable scene of all of Umineko as far as prime matters are the ones in late arc8. Namely…
-Ikuko and Tohya’s story after Ikuko found “Battler”.
-Ange’s story as a writer when she finally meets her brother (including the kinda clearly given explanation by Ikuko as to why to she wrote Ange as a fictional character in arc6)
-Battler and Beatrice’s scene in october 6th leading to them falling into the ocean.
Nonetheless two of these scenes have clearly … figurative scenes.