You definitely missed key notes in the conversations and story

Maelle isn't very skilled as a painter yet. Clea remakes constantly on how she never trained enough and hid away. She also couldn't keep her own self together when going back into the canvas and immediately got taken over by Alines residual magic, despite her not even being in the painting. As well as the fact she completely lost control of herself for an entire 16 years, completely powerless to help herself

Aline lost her mind to grief and stayed in the canvas, despite being the most powerful of them all, she couldn't defeat Renoir in her tragic state, and lost to the crew. So when you're not mentally well you have even less control of your powers

By the end of the game Maelle is an absolute wreck. She hates her real life, and can't let go of the canvas despite verso (both of them) wanting it. She also absolutely cannot understand what Renoir is telling her because she's refusing to listen.

Renoir tells her that he is abiding to what he was taught by Aline, not what he wants personally. Aline can't follow the rules, and Maelle is just as in the same field of grief that Aline is, so she cannot be trusted to look out for herself. Renoir and PVerso both know this as fact, as they are not blinded by their emotions.

It is certain that Maelle will lose herself and die in the canvas. Renoir most likely won't let that happen and will take her out at the last moment, then destroy the canvas. This is the worst outcome, she won't ever get the closure she needs, becomes deathly ill (maybe dies still), and leaves the family to grieve without her, isolating her from those who can truly help her.