Opening this one up with Sigil is a fun experience, too
.
It feels like there's *at least* as much markup as text, so, yeaaaaaah, it could probably use a bit of simplification to make it easier to parse.
It's probably blowing all kinds of CRe limits as-is. @poire-z has a few gnarly test books for these kind of things, so he may have some more useful input here.