@Linda108Perhaps there could be a help note that pops up as soon as the host chooses Private Room as the accomodation type, that says something like:
"Do you have more than one private room that you will be hosting?
If you have more than one room available and you want potential guests to be able to book them seperately, you will need to set them up as seperate listings," with a link to a help guide on how to link calendars, etc.
It does seem to be a common error. I saw someone yesterday who was letting an entire guest house with 16+ beds for $13 CAD per night.