Cutscene/Firefight voice language settings.

I’m a bit of a linguistic nerd, so I changed the language setting on my Xbox to Japanese (Inspired after hearing “INFECTADO! NUEVO ZOMBIE!” over some ones mic). This changes all the text and Announcer voice in Reach to the Japanese version (Overkill has never sounded more polite, btw) but the cutscene and Firefight voices I select are still in English. I checked the Armory, and there are indeed Firefight voices with the Japanese voice actors, so I am assuming that the cutscenes were also recorded with Japanese dubbing. Is there a way to access this via the game, or do I have to have a Japanese gamertag?