I'll be honest, I don't think I could possibly offer any feedback or notes on improvement. Everything was solid. Story structure, world building, composition, sentence structure, dialogue, visual elements, all were executed fantastically with a high level of polish.
The only feedback I could possibly offer (and you already know this) is just work on polishing the sound design. TBH, looking at the Discord logs, it seems like RenPy was fighting you for no good reason. A lot of the actions you were doing should have worked. Misbehaving volume aside, the only thing I'd ask you to do is look into sound effect modifiers and use them to your advantage! Fadein, fadeout, etc. are your friends :3.
All that aside, stellar first VN. Well done! 5's across the board.