What constitutes an "entity with a control behaviour"? Specifically, does it include the interrupts on train schedules?
My current game is vanilla, so it wouldn't have helped, but I have a supply train for defense positions which can visit several drop points before needing to restock. Since it's unpredictable how much of what each point will need the interrupt tests for quantity of each item below some number AND the current station AND if the supply point is open. The DNF decision tree means it's (if ammo low AND at drop AND supply open) OR (if bots low AND at drop AND supply open) ....
I exported a print to JSON and built it there, then imported it. The mod, if it handles trains, would be a godsend in another non-vanilla game.

Train schedules are a totally different system. Control behaviors are mostly related to the circuit network.

I have been considering expanding this mod, or one like it, to cover other sorts of entities, though.

If doable, train and platform schedules and interrupts are certainly a worthy target. Big factor being the DNF notation. There's also, however, the inability to reproduce the same set of wait conditions across multiple stops, or the ability to change the name of a station without completely recreating the stop and moving it into the correct position in the schedule.
With 2.1 giving platforms the ability to transfer between each other when in orbit, and adding the solar system edge as an 'orbit' point, I can see some complicated schedules for trading eggs for promethium science in growing bases.
You've already figured out the GUI part and how to serialize the setting in lua, expanding to schedules is probably easier for you than anyone else. Separate mod is probably a good idea though. Prevents conflicting edge cases from becoming an issue.