I know that articulate released some new accessibility updates, including making the hotspot-graded question accessible. Still, I noticed that when you select the hotspot you would like to choose as...
Hotspots don't have states because they are invisible to learners, but this doesn't mean they aren't accessible. You can specify the alternative text for hotspots in the slide's focus order, shown here:
As for changing the appearance of the hotspot indicator, we're working on a feature request to allow authors to customize its appearance. I've added this ELH post to the feature request, and we'll let you know as soon as soon as it makes it to our product roadmap!