Original Xbox - I'm only aware of Metal Wolf Chaos translation.
Xbox 360 - I'm not sure there's anything that needs translation If you want Japanese audio + English text for some jrpg you can check up the Asian versions to see if they have those options. Lost Odyssey Asian version is like that, but it's NTSC-J and PAL regions only afaik so you'd need jtag/rgh if your console is NTSC-U.