I'm a little fuzzy on the details myself, but my impression was that a "homeroom mom" (homeroom wasn't a thing, since we did everything in one room, so she was "class mom" instead) just pitched in on special occasions back in my days. I certainly saw mine maybe twice a year.

My DW currently fills a similar role in DD8's gifted classes. She almost never goes in, and when she does, she's called in by the teacher to help on a special project. It just so happens that they're baking tomorrow, and DW is going in for that.

However, DD8's homeroom has a class mom that seems to be there every time we go by. Again, I'm fuzzy on the details, but it's my impression that she's doing a lot of the things that an assistant teacher used to do in elementary school... because the state is too cheap to pay anyone to do it.