In attempting to change some of the wording a project I am working on (using string overrides) I wasn't able to properly modify the string "Not in a book" that is passed through Vertical tabs to the translation function.

On further digging I noticed that you are actually coding this in a Javascript call. It seems weird but I'm wondering if this is the reason for the problem and if the string couldn't be retrieved from your module instead of actually making a straight t() call.

Any help would be awesome!