The semi-open order of the events wouldn't really help with why it would be a lot of work to add an Aura dumps Richard mental corruption ending. It's the fact that Richard is woven into so much of Aura's IRL corruption.
Having alternate versions of the 'good' ending where Aura reflects most of the mental changes could be an option, but I feel like that isn't how it's planned, and it would be a lot of work. Having a partial corruption version of the 'bad' ending triggered in the mental world doesn't really work. That pretty much leaves the mental world having an alternate route added as a way to add an alternate IRL 'bad' ending. That would probably need major reworks for the happiness, key memories, and values rooms, along with changes to the relationships, appearance, and knowledge rooms and new scenes for non-Richard versions of many IRL scenes. All of which would be a lot of work.
If Aura-dev decides to work on that sort of thing, I would be all for it, but I'm also trying to temper expectations due to the work required to do an alternate IRL bad ending well. I also understand how you feel about Richard. I'm not keen on Richard or where Aura's personality is going. On the other hand, they both fit pretty well as 'demons' without any of the softness that many modern interpretations tend to add to 'humanize' the demons.
