I ended up using your plugin, although slightly modified. I’m using the term_group field (which isn’t being used for anything else, AFAIK) instead of the menu_order field. Perhaps you could update your plugin to do this? you wouldn’t need a new column to do it 😉
BTW, if you’d like a translation to Spanish, send me your .po file.
Also, please let me know if the updated version (0.3) works for you, so I can mark this issue as resolved. 🙂