Thanks for that guidance. While I was able to make the changes, the stat is not responding to the "auto" mode. It's strange because when I manually change the stat to auto (again, at the stat), thermostatMode shows "auto" as the setting in devices (the dropdown for Set Thermostat Mode still does not show auto, BTW). That was the case even before I made this change.
If I use the thermostat scheduler, setting the stat to auto mode and adjusting setpoints, the stat doesn't respond. Like it's ignoring the command. The current mode remains. So, even though the stat has an auto mode which can be set on the stat, itself, the driver doesn't seem to be able to do that.
Honeywell describes their auto mode as "auto change." But the setpoints are for heat and cold. The auto change thing would seem to apply to a single setpoint for a cutover between heat and cold, with some obvious builtin separation.
In the thread you sent, one responder switched to the Generic Z-wave thermostat driver. Is that worth a shot?
Again, thanks for the time here.