I think those settings are not in YAST but rather in CONFIGURE DESTKOP.
I do not have XFCE installed but I think you should find somewhere CONFIGURE DESKTOP under HARDWARE subsection find INPUT DEVICES in there you will see JOYSTICK settings.
I manage to find it at ‘imput devices’ under ‘KDE system settings’. Sort of what you said.
Although I am not sure I hat to have installed KDE. Anyways I will try to get rid of KDE and see if it works as well.
With KDE comes a tool to calibrate the joystick. This option seems not to be included on XFCE.
I may be back to say if it works without KDE installed.