Although the 2007 recipient of this award, Letters from Iwo Jima, a film almost entirely in Japanese, would not seem to meet the qualification of a "Foreign Language Film", the actual Japanese title of the award, 最優秀外国作品賞 makes no mention of language.
The winner of the 2007 award, Letters from Iwo Jima, a movie primarily in Japanese, initially seemed unlikely to fit the "Foreign Language Film" category. However, its Japanese title, 最優秀外国作品賞, doesn't explicitly refer to language.