I don't have any insight on the "best" way to implement this beyond writing your own Hubitat App, but wanted to commend you on what is clearly an ambitous project. I've certainly never even THOUGHT about trying to create a set of RM rules this complex before, and here you've not only thought about it but successfully implemented it.
While I have not personally used it (yet), it might be worth looking at the [BETA] Simple State Machines project. It is an implementation of a Finite State Machine for Hubitat.
So when I see people posting screenshots of their RM rules with multiple IF - ELSEIF - ELSE blocks with different conditions in each and they wonder why it doesn't catch an edge case, my engineer brain says "That's a place for a state machine!"
Since you clearly know all the various states and behaviors you're looking for (your visual flow chart is basically a FSM representation) it might fit the bill.
