I don’t understand where I’m going wrong.
I’m using Add Actor LOCAL rotation, but the rotation is not truly local.
I wish I had local rotation like in the editor. That is, the rotation about the actor axis. But this is not the case.
In the video I show how I would like to have the rotation (F8 edit mode) and how it is managed with Add Actor Local Rotation instead.
What should I do?
I could not see the whole logic in the video. But why don’t you try another approach. Don’t rotate the whole actor. Rotate only the mesh that represents this papper. That should work quite fine.
Btw. are you sure you are not using quat and rotator at the same time, and converting them in a wrong way?
Works fine here
I suspect there’s an issue with your rotation calculation function, you might be calculating rotation in camera space or object space, but you just need to give it untransformed values and AddLocal does the calculations.
The problem was on sending the coordinates in rotation calculation function. 
I got what I wanted by using local rotation for X and global for Y.