That is standard Homey logic.
Every numeric capability gets a higher/lower flow trigger generated.
But only main capabilities get default flow cards generated (value changed).
The app has two custom capabilities for generic values (measure_string, measure_number) wich such trigger cards. But also only for main capabilies. I think the trigger cards are coming up from these capabilities.
Ok, I’m using the measure_number for all numerics, since there is no standard capability for the number values I use. So yes, there are sub capabilities quite a few.
Until now I’ve used it to create different MQTT devices. Mostly ESP32 stuff. And they are working. Now I decided to add a descoverable device. I "manually” published device properties to its topic. The device is discovered, but never gets update. In the MQTT Explorer looks like:
But when I “manually" (with MQTT Explorer, for example) set the value for the homie/lightsensor/light-sensor/measure_luminance, in the device card it is not updated.