I don’t know what new progress is going on to fix this with the newest homekit binding development but check out this thread for information on that.
As for assigning rooms to HomeKit - this is done only through the Home app on iOS when adding things.
If you’d like a more stable options check my answers in the post here (note the first option is the same as what I linked above).
Personally, I use node-red to connect my openhab to homekit, it works great and hasn’t once “forgotten” my room assignments as the openhab binding did often.