xfburn have these files: po/en.po po/en_AU.po po/en_GB.po I suggest removing en.po since the others are there. en.po have all identical source/translation strings.
Romain Bouvier referenced this bugreport in commit b51581a636f8d77bd881aacc86eb80159d349c8c Fix bug #15545: Remove useless en.po file https://gitlab.xfce.org/apps/xfburn/commit/b51581a636f8d77bd881aacc86eb80159d349c8c