I was able to recreate the piston above in RM, so all my device automations are now on HE 
I ended up removing Harmony from HE, I don't want to maintain and sync it in two places and I don't have a good way to get instant status updates in HE, where I do in ST. The only thing I need to know for my HE automations is if either of my two hubs has an activity running, so I created a virtual switch that gets turned on by ST whenever an activity is on, and used that to run my automations in HE.
Harmony instant updates, Google Home, and one IFTTT webhook that uses webCoRE as an intermediary are the only things stopping me from shutting off my ST hub now.