Just tried to disable it a few times on enwiki, but it stays enabled :/
The Book Creator doesn't seem to take into account the new setting (enable/disable) until I go to another page. If I go back to the same page, the setting remains ignored.
- go to https://en.wiktionary.org/wiki/marque-page
- Click on create a book (a new page appears)
- Click on the button "Start book creator" (go back to the previous page)
- The page doesn't show the Book Creation banner (the link to the Book Creator remains as "Create a book")
- Going on any page next (e.g. https://en.wiktionary.org/wiki/bookmark) shows the banner and a the behavior is as expected
- However, the banner remains hidden when going back to the first page...
The same thing happen when I try to disable the Book Creator.
Confirmed on hu.wikipedia but on en.wikipedia disabling seemed to work correctly. As Darkdadaah said, the book creator box will be visible on the page where you return after clicking the red disable button, but it won't be visible on the next page.
Tentatively closing: I was never able to reproduce this. It might be a matter of patience, because it takes maybe a couple seconds after the initial loading of the page for the book creator to be displayed (followed by the audio player).