This is seriously the first Taxonomy plugin I've found that wasn't full of PHP notices. THANK YOU!
A couple things.
1. You do have SOME PHP notices that you should fix. Here's one I found:
Notice: Use of undefined constant SCUST_VERSION - assumed 'SCUST_VERSION' in /path/to/wordpress3/html/wp-content/plugins/simple-taxonomy/inc/class.admin.php on line 74
2. Consider removing the whole label section of your form and instead just ask for the singular and plural name of the taxonomy, e.g. "Genre" and "Genres". Then use those to generate the entire list of labels.
3. You need to finish your localization of this. For example, in your Settings page, you still are printing the French: "Modifier | Supprimer" instead of localized strings (e.g. "Edit | Delete" in English).