Just because he is Japanese, doesn't mean he declares his special moves in such a way that is typical of other fighters (hadouken,tatsumaki senpukyaku, etc). Headbutt = doof goy which is 'gibberish' whether you think it makes sense or not. It's like saying HIYA emphatically while doing martial arts; you're not going to interpret it as something else just so it sounds like a word. Also, buttstomp and ochio throw = diggit, hundred hand slaps = HOOAH HOOAH HOOAH repeatedly (which in sf2, was just the male throw sound looped), and taunt is also = doof goy. As intel already pointed out, it's been like this in every game he's been in: sf2, cvs2, sf4, etc
I don't care if people discuss the sound in the mod, because it's still an aspect of it.