Hello Tom,
I'm Eduardo, from Brazil, and I can help you. I have a good experience in English-Portuguese translations, as you can check in my profile. Also, I'm a coder here in Brazil, so I can work with your XML file with no problem. I can send you a preview of the work from the file you attached if you need to test my skills. Finally, one of my hobbies is to play the guitar, bass guitar and keyboard. I've studied music theory, so I can perfectly translate your app. I can send you some pictures of me playing, that's the only way I can prove this part for now.
Please let me know if you have any question.
Best regards,
Eduardo.