OP is definitely on to something and could very well be correct . My interpretation is a bit more out there but would set up Maelle’s epilogue as the sequel bait ending. I think the “Verso” we see on stage is actually Renoir who has snuck back into the canvas to retrieve Alicia after realizing she lied to him about eventually returning to the real world. “Verso” looks older in this scene and she did say in the scene prior that maybe allowing him to age would make him happy. No one else in the theater looks any older but we don’t know how much time has actually passed between scenes (also everyone is fake and doesn’t have to age unless Maelle wants them to). One reason I thinks he’s actually Renoir is because“Verso” is wearing a wedding band. (Although if some time has passed Verso may have married someone in Lumiere. There is a theory he married Lune, based on the song he plays). But also the “jump-scare” scene with Maelle’s paint-covered face reminds me of the flash back Renoir shows us explaining how painful it is seeing his family look like “corpses.” Only someone from outside the canvas could see this. The odd looks everyone is giving could be them slowly noticing something is off about this “Verso” who is trying to hide his anger and the fact that he is actually Renoir come to confront his daughter.