I truly love mystery manor games! I like that this was translated. I like the film noir atmosphere. I like the "dark and stormy night going for it. I like the mystery notes and the puzzles as well as the mechanic added to this game to see invisible clues.
However there were issues I've had with this game.
#1 was the lag. The lag makes trying to solve a puzzle just drag on, like it's taking forever for the asset to move towards its designation. This is especially bad for those of us who are replaying the game for the other ending. I know you're using Unity, so I'm not sure what would help cut the lag...maybe the background animation frames could be cut down so less is loaded??? Not sure how that works for games, I'm going off of my gif-making experience to see if this is basically the same case.
#2 is the Heart meter. The stone still drains it too quickly. I know you said you would update it so that it's slower, so my only suggestion would be to let the meter gradually refill the more we don't use the stone.