Thanks to all those who helped out. As usual, many of the comments were more interesting than they appeared at first sight. The most helpful are comments which (1) address the mathematics directly, (2) point out precisely what the problem is, (3) if possible give a definite suggestion as to how to fix or improve things, (4) are left on the page of the smallest unit that is being commented on (so if commenting on a lemma go to the webpage that only displays that lemma). You can leave mathematics in the comment (using latex) and when this is done I can steal your latex code when I make my edits which helps! Of course, the editor for leaving comments isn’t perfect, but it mostly works.
Another thing: if people ask questions about the mathematics, I don’t always answer those questions. But you, dear reader, can answer those questions too. I welcome that!