Thanks so much for playing my game, and thank you for letting me know about that bug!
Since it can affect the intended puzzle experience, I'd definitely like to fix it in a future update.
As for the final level... I actually agree with you. Looking back, I don't think it's the most satisfying kind of puzzle, since it relies a bit more on trial and error (or even luck) than on pure logical deduction. To be honest, even I, as the creator, don't feel it's the strongest puzzle in the game.
That said, it was the toughest stage I had managed to design before the jam deadline, so I decided to use it as the final challenge. Thank you for sticking with it and making it all the way to the end!