Alt Text for a Single Storyline Slide with Multiple Zoom Regions

My first instinct is separate slides or layers, and I don't think zooms work well with layers.

On the other hand, additional slides are free The way I read your question, most of the complication comes from having so many complexities on the same slide.

Create one thing on the slide, duplicate the slide, and change the text and alt text. An added benefit is cleaner faster workflow, along with less complexity.