Thanks for the very insightful feedback! I mean it. This is my first non-visual novel game, so my balancing definitely needs work, feedback is more than welcome.
I'll look into changing the vent to shine flashlight automatically without needing a choice, that won't be hard to implement at all. And sure, I'll make Claire immediately start helping without dialogue. I will also add sound effects for when some of the ghosts spawn (edit: I tried doing this, but didn't like it because the sounds became obnoxious). As for intuitiveness, I've already added a new in-game tutorial that will be released later this month, so hopefully that'll help.
The enemy "reset" you mentioned is something I planned as an "upgrade" that needs to be unlocked at Day 3 (in fact I'm working on it right now), still not 100% sure how to implement it, but I think it's possible. I might try different things depending on how it goes.
Regarding being attacked during a cutscene, I'm not entirely sure what you mean, but I'm assuming you mean during things like collecting essence. That was a conscious decision, because it would be too easy if you can just recharge your essence, power, or pleasure gauge while being safe. I wanted to require the player to check all the threats before doing these "recovery" actions. These recovery actions are not mandatory, and there's also casual difficulty where it is impossible to lose.
I noticed the button responsiveness issue too, and unfortunately I haven't been able to take away lag completely despite already taking steps to optimize. I guess since Renpy is an interpreted language, it just can't do things as sharply as some of the other engines can, but I only know how to do Renpy so it can't be helped too much.