Thank you so much for the criticism! It's great to get more readers and know what others prefer! After I made the original nanoreno demo, I only received two comments more detailed than yours, so again, I really appreciate it!
I made the demo to start in the middle of the story when the string of murders begins. This is so demo readers could jump into the mystery instead of wallowing through the setup. The setup will be focused on the Slice-of-Life side of the characters and story, hence the cutesy sprites. I've played horror VNs where they used close-ups of bgs, and I assumed they were used to give feelings of claustraphobia. Maybe I'm using the bgs incorrectly, so I'll keep that in mind to either limit or get rid of them.
One of the most common criticisms of the original demo was how short the scenes were in the game, as there weren't enough characterization and character appearances, so I expanded upon those scenes in the most recent version, albeit maybe a little too much. I also felt unsatisfied with the lengthy scenes, so I agree with you. I'll keep that in mind as I write further.
For instance, in the original nanoreno demo, the trial scene was nonexistent, and readers gave suggestions on how I should write the trial scene. I followed their suggestions, and yet I felt there were some elements which made it lengthy and I wasn't sure why. You pointed out the repetitive bgm, so that might be one of the reasons. (I was trying to find several suitable royalty free bgm for the trial, but I couldn't find any similar enough to complement the two bgms I had) . You also pointed the lack of player interaction, so that might be a good idea to add more MC participation, especially to the trial, just to break up the passages even more.
As for now, I'll continue progressing the demo and will come back to fixing these scenes once I'm done finishing this major route. Thank you!