I manually upgraded the firmware from 1.1 to 1.2. This added some features but didn’t solve the PDF problem, where the images of Google Books show as red xs. (Using the now-available store to download these books gives me the typo-riddled EPUB not the PDF.)
I opened one of the offending PDFs in the default GNOME/Linux PDF viewer and “printed” it to PDF. The size ballooned from 1 to 31 megabytes. It works but not well: the text is grainy and the original page size is superimposed on a letter-sized sheet — if that’s even a meaningful statement. I’ll find another way.
I’ve installed Calibre, a ebook manager. I’ll see if that can do any good.
I can’t find the six-year-old file that I used to generate the PDF of James Relly’s Union. That’s what I planned for generating an EPUB, with pandoc. But I’ll keep looking or use another Relly title as a trial first.