is all your feedback based on the final boss or do you mean the timing is off overall? Are you using a controller or the keyboard?
I am using the keyboard, and I mean the final boss overall. Especially when I need to guide the rook from one side to the other. When the rock falls, the Fact attack makes it bounce, but the bounce is unreliable. And when I manage to get it to the side, the boss is already leaving to the corner and I can't get it to bounce high enough to hit it.
The rest of the game, no problem and I had a lot of fun.
I'm sure you'll get it if you try some different strategies :) but if you'd rather just see, here's how to beat it: https://www.youtube.com/watch?v=m2FWumhyHC8