Stealing from @robertbrook's idea (no change there)...
Could it be worth writing a routine that jumps through all the info.js files (or at least, all the ones that don't have the completed attribute we're looking for and checks the ISBN against openlibrary.org. If there's a cover image available, add the line openlib_cover: true AND (optionally?) output a "report" to the screen of books that will need a cover.jp(e)g file to be dropped into the _meta folder?
Stealing from @robertbrook's idea (no change there)...
Could it be worth writing a routine that jumps through all the info.js files (or at least, all the ones that don't have the completed attribute we're looking for and checks the ISBN against openlibrary.org. If there's a cover image available, add the line openlib_cover: true AND (optionally?) output a "report" to the screen of books that will need a cover.jp(e)g file to be dropped into the _meta folder?