Without the nesting it seems to be very reliable using proxy switches and rules to control the situation as I posted above. I’ve posted my working setup in the older thread Group status updating from top-down but not the other way. I’ve leaned a lot since that thread was started 
You time spent advising is much appreciated.
As a side note, I spend months away from home at a time and I haven’t set up remote access to my Pi, so I just leave it there running OH2 minding it’s own business, In all those months it hasn’t missed a beat! So however much we throw questions around this OH2 machine, I can certainly say it’s robust!
I’m running a hue bridge, a Wemo bridge, a LIFX bulb and a Z-wave stick, all unsupervised. Credit to you guys who are creating something special here