ALL faders and ALL buttons should already work. Why don't they? They should all send something via MIDI.
You could let them send on different MIDI channels but this is not required, since I expect them (specially the faders) to send all different controller numbers.
A special version for MS FS 2020 will come! And everything will be possible to read and write. So some values can be manipulated by MIDI-faders directly like in train simulator and not only by +/- defined keypresses.
But You have to wait for this.
I can not tell, when this feature will be available, You have to check the development roadmap inn this forum fromtime to time.
Evrything is prepared and I know how to hanlde those events.