I had the navigation buttons enabled and take captions from tab titles disabled and the next and previous button custom captions didn't work until I modified:

(Drupal.settings.tabs.navigation_titles

to
parseInt(Drupal.settings.tabs.navigation_titles)

in tabs.js

Any hints on this?

Comments

I haven't had any luck overriding the button titles. I tried your suggestion with no luck. Currently buttons are inheriting tab titles even with "take captions from tab titles" disabled. I have my override set to << prev and next >>.