Ok, I found out how to edit speed along curve path.
But I did mistake, I should have made speed differences along path first, and after rotation- lean angles.

My graph editor looks like this now, middle line is path, speed and the side line is leaning angle line.


When I edit middle line (adding points, stretching..) it also affects points of leaning angles, even if lines are separated.

I guess it is possible to make those two lines independent ? Or lock "leaning angle line" so it woudnt be affected ? how to do that, thanks.

---- actually those are independent, in that graph, I can select them separately, but still same problem edditing one affects others point positions..