Welcome to the community, yakkyetc. I'm sorry about your mom.
Alzheimer's medications like Namenda and Aricept don't normally improve symptoms, but they can slow the disease's progress. It's always hard to tell how well they're working because you don't know if the person would be worse without them.
One of the sad things about Alzheimer's is that patients often don't find a lot of pleasures in their lives, and even less so as the disease advances. It sounds like you've done well to find some things that do make her happy.
It's wonderful that she's been able to find joy in some new things since her vision has improved so much. If you think about it, if you couldn't see very well, it would be quite isolating and probably depressing, which would certainly affect your ability to find happiness.
Music can definitely be soothing and uplifting for an Alzheimer's patient. I don't know how often you play music for her, but maybe it would be worth a try to have it going in the background when she's awake.
Most Alzheimer's patients love talking about the past. Maybe you could interview her now and then, and record what she says. She would probably enjoy it very much, and it would be a nice record for your family to have. Or maybe the two of you could work on a scrapbook or photo album together.
Jigsaw puzzles can also be entertaining -- maybe one with sort of large pieces.
Does your local Alzheimer's Association or Senior Resource Association (or whatever it might be called where you live) offer day care or activities for people with dementia?
You might contact your Alzheimer's Association for other ideas.
Please don't blame yourself if it's hard to find things that bring your mom pleasure. Unfortunately, it's the nature of the disease -- making it worse is that a lot of dementia patients also suffer from depression. You seem to be making a real effort, and that's the best anyone can do.
I hope you'll continue to post here and let us know how things are going.
Best wishes-
Carol