The localization files are working. However, I have two issues with the translation in email notifications:
1. The string 'Username is now following your activity.' is not in the pot file.
2. The two other strings 'To view Username's profile' and 'To disable these notifications please log in and go to:' are not translated. In other emails (e.g. friend request or message notification) they are translated using the BP po/mo files.