Operating system conventions that affect accessibility are those described in this document and in platform-specific accessibility guidelines. But it sounds, based on discussion today, that users with CD are affected. Yes, too much visual information can cause problems. Yes, that's a possibility. If you want to talk about learning theory, you're dealing with different types of information.
Research shows that transitions between modalities can be a very difficult task.
I would suggest that this be moved to a P2. Yes, flopping back and forth between modes. The lower challenge may be pure text or pure image. Images aren't bad, but complexity can be bad. This is not a mere clarification to the document.