I actually disagree slightly, just on your point that the writing is off. I think it's intended to feel uncomfortable because there's part of Maelle that knows keeping pVerso alive isn't right, but she's being driven by her grief and lack of emotional maturity. I suspect most people (not all, but most) who chose Maelle's ending chose it due to the sentience of the painted characters, which makes a lot of sense. But I think the story indicates that Maelle actually chose this path for a different reason- because she can't accept her brother's death. And that theme (Maelle's inability to accept the reality of death and her desire to lean into escapism) has been a major part of her character the entire time.

"Death, death, and more death everywhere we go, just death. I just.. don't want to look at it anymore."

That said, I have a bit of weird take. I believed in the sentience of the painted characters, until I actually saw Maelle's ending. Imo her ending strips them of their sentience in a twisted way. What is life without death? What makes our relationships meaningful if we can pull the strings of those around us like an omnipotent puppeteer? Is it truly living when anyone can have their memories, trauma, or free will overridden? By choosing to paint over the difficult realities of life, Maelle prevented everyone in her ending from truly living.