[before reading the guide] couldnt find the blue door key after running around for about 10 minutes .
at this time i didnt know about the camera flash thing and ran into the ghost guy after collecting the key in the piano room and then game crashed.
After i replayed, i came to give feedback and then i read your guide on it in the comment section and Im pretty sure i tried to interact with the piano but nothing happened.(no prompt or any indication i had done something).
Maybe after you pick up the key the piano makes a sound so it would give the player a reason to think about interacting/inspecting the piano?