Thanks!

Sorry, from your wording I'm not sure whether you are suggesting custom tags or saying there already are, but to clear up any confusion, there will be.

That's kind of what I was hinting towards at the end of the demo - you can define custom tags and styling behavior (either globally or at a block level, or site-wide in your preferences) with keywords like "@"

Trust me, I know the struggle of setting up like 500 custom math and environment macros in LaTeX. I'll try to find the best solution for this sort of thing - Polymath should work very well out of the box, but it should also allow for a fair amount of customization.