The bug

Chiseled bookshelves' step.chiseled_bookshelf, insert.chiseled_bookshelf, insert_enchanted.chiseled_bookshelf, pickup.chiseled_bookshelf, and pickup_enchanted.chiseled_bookshelf sound events do not have their source category defined, so they use the Sound category.

To reproduce

Mute all sound categories except for Main and Sound. Jump around on some chiseled bookshelves, and place and remove books and enchanted books from them. Observe that they make sounds, despite only the Sound category being on.