Hello,
I realize this is an extremely specific issue that involves other Unity plugins besides AC, but I think the problem MIGHT be most easily fixed on Adventure Creator's side, or at least a workaround could be found by asking about it here.
Super Text Mesh is a handy Unity plugin that acts identically to Unity's default text UI element, except it understands many more hypertext commands- mostly for animating letters, like this:
In theory, it should be able to be updated just like a normal text UI element from Adventure Creator; after all, it functions just like normal text, just with some added tags and animation. However, it doesn't actually inherit from unity's text objects, so it won't work with AC as is.
One workaround would be to make AC instantly update a (hidden) text object, and then have STM read from there. But that's really inefficient and seems like it'd be kind of a headache to set up. (I could also always make a getter/setter, but again, seems inefficient and might be hard to hook up so it updates nicely as characters are speaking.)
I think the best way would be to create a new element type that works with Super Text elements. How would I go about doing that? I'm not afraid of diving into the code, I'm just not really sure where to start.