Just to close this out ... after going through a bunch of gyrations and trials, the best way to "fix" this is to use the Google Home. It can activate MH scenes, so when we want those, we just speak it..
Kind of sucks that there's no way to activate MH scenes through EISY - or to directly address colors and functions but this appears to be the simplest, most reliable (albeit with a pretty significant lag - 21 lights go on over a period of about 10 seconds), and most "spouse acceptable" method I've been able to come up with.
Now I've added a couple of Govee lights (thanks Amazon Pride Day) which are very cool, but the Govee poly doesn't work with them either. That's another thing Google Home was able to address - automations can directly address both MH and Govee in the same command.
I *hate* not having everything addressable via a central app and having to go through multiple apps to control things (Automate for shades, MH for scenes, Govee for those lights, and Eisy for everything else) but with Google Home acting as the speech front-end, it works.
I'm still fiddling with Home Assistant - it appears to be able to do everything I want to do, but it's a lot of work and time isn't something I have enough of for a while!
