I don't know if the writing troubles are with a specific part of the content or all around, but maybe it would help to re-examine what experience the game is meant to deliver?
I can only speak for myself, but considering this is similar to games like "Princess maker" and "long live the queen", I wouldn't mind the writing being focused in "quantity" over "quality". I mostly would just want the endings to reflect what I built the princess to be in that playthrough (her main mood, most developed set of skills, her relationship status, corruption, etc), if the trouble is with integrating all of that in a cohesive way with strong narrative pieces, I'd say to just give up on that and go with a more modular approach, like little vignettes just for the purpose of highlighting whatever traits of the princess.
What I'm thinking is that what remains of the story should be:
Climax event -> Election result -> Epilogue vignettes -> Final scene focused on the Princess' relationship status
The climax events are mostly already setup, iirc it was either demons, barbarians, or noble conspiracy. I don't know if the writing struggle is here, but I'd argue to not overthink it too much. I know they are the "climax", but for these types of games that are all about "tailoring" your protagonist, I don't think they need to be much more than just "the final hurdle" before the endings, which are the real payoff for these types of games (I think you kind of need to treat it as the opposite of how you did "Calibration Error", where the "ship of theseus" scene was the big focus of the narrative while the endings themselves were more "for fun")
Can't imagine the election results being a scene that would cause much struggle, just the councillors expressing their approval or disapproval of the princess and the brother reacting to it.
Like I said earlier, if you make little epilogue vignettes it should be easier to just write random scenes to feature traits of the princess, without worrying too much about how they might conflict with other elements of the story. At most just make a variation for if she won the election or if she lost (so she is either a queen or not).
Capping off the endings with the "relationship status" would make more sense since I feel the stronger narrative aspects of this game are in the specific routes and relationships, also lets you have the "money shot" of the ending with whatever final art piece for each romantic partner/route/scenario.
But ultimately this is just me sharing thoughts on how I'd like to see the ending of the game structured. If the writing block is more with having to write specific scenes or characters, I will just go back to my opinion that quantity over quality is fine here. With the replay value and sheer number of routes, even if some scenarios don't end up quite as good as you may have wanted them to be, just being able to wrap up all of it will already make it a pretty great game.