Good find and good analysis
I have the exact same problem as you do. TTS on the satellite just wonāt work although I have everything set up correctly.
My satellite is a Raspberry Pi 0 W and the host is a fast linux serverā¦
This worked for me also to some extent. When I press the speak button using the satelliteās interface I get a spoken response but any commands to not return a spoken response. The wake sound works and the intent is handled in Home Assistant, just no verbal response.