Gallery with lightbox

I’m using the f8 light theme with the standard WP gallery.
Just wondering how to tweak the caption to display the title on the gallery page and description + title on the lightbox popup?

I found the code snippet to swap the $attachment->post_excerpt $attachment->post_title in media.php but that seems to remove the post_excerpt in the lightbox popup as well.

The page I’m talking about can be found here