I've fixed the music room bug and I've already seen the problem with the secret ending, I've already fixed the fact that you can't enter Yuri's room and I've made sure that you can go up the stairs now, I apologize for those mistakes, I don't understand what happened when I tested, I could swear that everything was fine, I must have made some change afterwards that caused that bug and I didn't notice, I'm very sorry.
I'm afraid it's going to take me a while to compile, since I'm finishing the update of another of my games, but this weekend I'll definitely upload an update with the fixed bugs. If you know of any more bugs, please tell me if you're okay with it and I'll take advantage of it to fix as many as I can.