whatever you do in jstest-gtk has no actual influence.
Centering sticks there, and starting with centered stick does help, but only because the FPV freerider has a defective calibration method. - there is normally no need for another application, or considering stick positions when starting an app.
The asymmetric range is not correctable anyway - due to broken calibration.
*no* other application I ever tried, behaves this bad - for example, I can just use, after one calibration, the interlink with X'plane - or use yoke and throttle quadrant for FPV Freerider with same pile of problems - that no other simulator or application shows.
I am not asking to hop thru loops to make it work, just hoping that the author cares to add an actual calibration routine that just works.