I see, you’re right.
Note that in the height in [-1, 1] is to, so if you want to move 20 pixels in y position you should take
2*(y/128)
This works for me (note where is the red line in the first image)
image709×732 46.3 KB
And in general for the other related transforms this work in the same way. Keep in mind that the coordinates are scaled to -1 to 1 in the transformation.