Got some decent sleep, and lo and behold, the things that were causing me such problems were fixed super-easily today! Sleep: An actual miracle cure!
I ordered a new proof of the trade paperback. I’m kind of thinking there will be another because it’s kind of hard to know if you put the chapter ornaments in the right place without an actual book to look at.
ETA: I decided to resume work on the large-print edition—whew! I finished laying out the first five chapters, and then basically on a whim I proofed them. And then I realized that, oh, yes, one must proof a layout every few chapters, especially with the large-print edition, because I very nearly lost a page—I managed to avoid having to lay out a couple of chapters again from scratch, but it was very close thing.