Well, if I do understand id well, what you said, then you did just rename the variables in the php-code from whatever_lightbox to whatever_favorites - which makes no change to the function and lay-out or design at all
A variable containint the url to your bookmarked pictures will be allwaya a variable containing these data, no matter if it is called "url_favorities" "url_album" or whatever else...
If you do replace text in main.php of your language pack from lightbox to album, the galery will show you "album" instead of lightbox...
but to be sure: you MUST NOT change the name of the variable, but the variable itself...
example:
$lang['lightbox'] = "Lightbox";
$lang['lightbox_no_images'] = "No images stored in your lightbox.";
etc.
red - must not be changed - name of the variable
grenn - might be changed to whatever you want to call your lightbox...
And the next step is to edit all the button-images saying "lightbox" to anything you want to call it instead...