This is awesome! I also have an aprilaire thermostat and have been frustrated by its painful lack of smart home integrations.
There is a HACS integration that was recently released that talks to Aprilaire locally. Community thread here and GitHub repo here.
It works pretty good but it doesn’t support multiple zones yet (it technically does if you have two thermostats but it doesn’t if you have a support module).
EDIT: I just caught up on the thread and see that you already posted in it and your specific issue raised. My bad.