I believe there is just one FX track, and not one FX unit per track. So in its current form I think it’s not possible to apply FX individually to each track output.
… But the FX track is digital after all, and who knows how much CPU power and memory is left on the Analog Keys… I wouldn’t put my hopes into 4x effect tracks instead of one, but every digital aspect of the Analog Keys can be fundamentally updated in an OS update.