Unfortunately if you are unwilling to apply fixes to your site, there's nothing more we can do on our end for that. vBulletin made it so you have to enable debug mode to view normally hidden settings. I made a suggestion that should do this without affecting your whole site. This has been fixed on our end.
You are right, someone seems to have deleted the IMPORTANT part from our documentation for setting up the Book namespace. It's pretty simple, once you've created it, find the row called "Book namespace" in the "Namespace Functions" box. Select the namespace you want to save your books in.