I think I understand more clearly now what you’re trying to do. I’m glad you’ve worked out a passable solution. I do have two thoughts-ideas which I’ll pass along for what they’re worth:
I think there is a way to map four Midi controllers to act like the Zynthian encoders. I don’t know how to do that, perhaps somebody else will chime in.
The most flexible way you can set up controllers is through the recent addition of ‘controller drivers‘, here’s the topic where they were introduced: