E6000 will do the job, but its also hard to apply it edge to edge without any seeping out. For this project I think that a flat 2-sided adhesive sheet or an adhesive spray would be better.
I would test first, but my thought is to spray the back of the leather with 3M 77, apply to the book, and then apply even pressure overnight.
https://smile.amazon.com/Super-Multipurpose-Spray-Adhesive-AB-530-4-77/dp/B0131SZ660