I apologize if this has been suggested, or if there's a general requests thread I've missed skimming the pages, but I think this would be a good addition.
Case in point: https://www.gearogs.com/gear/89323-devi-ever-fx-bit-mangler
Technically, this type of joystick is built from a matrix of 4x rotary pots. Thus, "rotary pot" was the closest approximation, but that seems like an imperfect compromise.
It might also be useful to differentiate between "rotary joystick", or some other term, to describe an "analog" joystick built on a matrix of rotary pots, and "joystick encoder", which is what I assume the Korg Wavestation uses.
Thanks for looking.