I can answer, and add a question for Janet. Koho tento is when you drop and roll backwards, from hip to shoulder, very gently. We usually do a few rolls from suwari, then a few more into handachi, and finally into tachi as a warm up before we do the more intensive rolling and sutemis.
For Janet though, I am wondering if you do more than that, since I haven't heard koho tento used with waza after it.
In Ki Society the various exercises had the suffix "undo" and for some reason when our dojo went unaffiliated it got changed to "waza." I forget it's not common usage!
Our Low Impact class doesn't require any floorwork but I've generally had students who could do this and really enjoyed how it felt, and I feel there is a huge benefit in adults relearning being comfortable on the ground whether or not they are able to take full-out rolls and falls.