After a long search for the code where the driver integrates the joystick controller, I found (surprise! surprise!) that it's all just inherited from the default INDI::Telescope implementation. Finally, a lot of the undocumented settings make some sense to me, as well as the terms "angle" and "magnitude". On the other hand, most of the limitations seem to be based here. Since it is the work of Mutlaq personally, the reason is definitely NOT any lack of competence in this case... The "magnitude" plays no role - it just starts movement when above 90% (and stops when below 50%?). So, trying to program the joystick to work around the INDI system seems as crazy as just playing with the code of the method Telescope::processNSWE() myself. Or maybe is the whole idea of mine to control the speed by the magnitude of the joystick just for some reason bad?