[WS64]

That is the default actually.
First it tries to get the cover from the book (if you have it set up like that), then it looks for your custom picture (if you have it set up like that), then it displays "suspend".
You should check if you get different pictures for different books, best to test on search and a long tap on the results. But you can also see it by looking into koreader/temp. If you see an epub directory you are not up to date, if you see something like #mnt#sd#path#book.epub.jpg (a few of them maybe) everything is fine. This directory also holds the metadata.koreader file.

Oh, I overread the word "poor"... What I wrote is the case for "no cover image found"