There are two separate issues regarding reliability.
(1) the ZRTSI II is Z-Wave non-plus, which some don’t like on their Z-Wave mesh.
(2) the Somfy RTS radio transmitters are not terribly strong. The ZRTSI II has this issue, as does the Somfy myLink (WiFi) hub. The transmit distance is about 50 feet, not far enough for our home.
For issue (2), you can use Somfy RTS repeaters (part #1810791), regardless of whether you use the myLink hub or the ZRTSI II. I have two RTS repeaters.
There are a couple of ZRTSI II drivers for Hubitat that work fine. I used the driver by Justin Walker (@augoisms) and never had a problem with that driver. My ZRTSI II sits in the closet, unused, because I pulled off my Z-Wave mesh in order to get all non-plus devices off for mesh reliability.
There is also a driver for the myLink that works well with Hubitat, and is what I use. It’s a bit odd to configure, but that only happens once. I could give you a pointer to that if you want.
The way to control the Somfy devices with Hubitat from Alexa is to have a virtual auto-off switch exposed to Alexa from Hubitat, one for each button on each drape/shade (up, down, my position (stop)), then, have a separate Rule triggered for each virtual switch turning on, with an action to issue the appropriate command to the ZRTSI II driver (up, down, stop) for the desired drape/shade.
