Today's aircon adventures:

1. Switched the dining room cassette to "normal" airflow, which is more downwards. For some reason "up", not "normal", is the default.

2. Made a little remote temp sensor with an ESP32 and a Temp+RH module for the dining room. I've got this configured on the indoor unit's ESP32 adapter. I'm now testing to see how it behaves.

I'm hoping this will reduce some of the short cycling behaviour that I think is due to air stratification and these units are located on the ceiling.
Early signs point to yes.