You know, it's not like Umineko never made me thought about that since it's filled with concepts that are very well known in modern and post-modern theatrical drama, but your story is getting even closer to "Six Characters in Search of an Author".
Have you ever heard about it or seen it?
It's the story of six characters who somehow manage to appear in the setting of a real world drama company offering to tell them their story and asking to be impersonated (hence the title).
One of the main point of this drama is the fact that no matter how much the actors try to portray them or how much the characters try to explain themselves, the acting inevitably fails to capture the essence of the latters.
You can read it
here if you are interested.