About comments. There is added spacing between paragraphs now (two lines instead of one). In the html view, it's displayed as
<p style="yada yada"><br></p>. The problem is, I cannot find a way to bulk edit those breaks. Bulk deleting
<br> removes
all the spacing between paragraphs. Bulk replacing
<p style="yada yada"><br></p> with
<br> doesn't work at all. Is there a way to remove excessive spacing (leaving one empty line instead of two) without doing it manually for every book separately? I have thousands of books with this problem.

Could never manage to do it one by one.