@davidfor, as far as I'm concerned you can roll a beta with the added Pocketbook support.
When you have the time, off course. No hurry
Matching for PB is done now using the path, with fallback to author/title or just title.
When things are added outside of calibre, moved around and changed, some extra handling is required. As on my unit...
Beta testers should enable debug, and pay attention to lines with "_read_database_annotations" and "_fetch_annotations".
BTW, changed were also the "book_mi.author" definition (this seems to expect a list of authors?), and authors_fixed was added to "installed_books_by_title". A bit of a hack to be honest, but it doesn't seem to break anything.