Touchscreen mouse speed much slower vertically than horizontally?

Hi guys, I've got a little problem with the mouse speed: I have an RP2+ and want to control the mouse pointer with its touchscreen. This works generally but the vertical speed is about 4 times slower than the horizontal speed, which makes steering quite awkward.

I can adjust the overall mouse speed at "Core Options -> Input -> Mouse Speed" but this affects both axis. The problem seems to be more the vertical speed, because even when I crank up the mouse speed to 300% I still need almost the full screen height to move the mouse pointer from top to bottom, while horizontally it's then only about 1.5 cm for the full width. The problem seems to be with PUAE because when I use the ScummVM core mouse movement works normally.

Is there any way to fix this, like to adjust the vertical and horizontal speed seperately?

Start by reproducing the touchscreen behavior on the RP2+ and trace the Core Options → Input → Mouse Speed setting in PUAE, comparing it with the ScummVM core where movement works normally. Done means vertical and horizontal pointer movement have consistent scaling, or separate controls are provided and the behavior is verified at multiple speed settings.