Thanks a lot! That was great input.
While reading about uinput the idea of writing to the event itself instead crossed me.
I implemented a function that generates the various (basic) events of a touch screen and writing it directly to event0.
It works perfect so far.
That doesn't really help. I know the difference between the 2 devices.
The issue seems to be in the path and maybe the resulting timing Qt (QWS to be more precise) gets the XY position compared to the path over which it gets the click events. This seems not to travel the same way from DFB to QWS.
Still have no solution for this.