It's a known issue. The solution will probably be using SQLite3 to remove from cc.db database or at least hide KUAL "book".
Search for posts by @knc1, mainly in KUAL topic (read last 5 posts) for more info:
https://www.mobileread.com/forums/sh...postcount=1875
I other words you'll have to wait "user-ready" & "MRPi install packaged" form.