Posts on Super User must be written in EnglishSuper User must be written in English. British, American, doesn't matter, so long as it's in English.
If they are spam, then flag as spam.
If they're not spam, then flag as "not an answer" or a custom message pointing out that it isn't written in English.
These posts will be deleted.
If you wanted to translate, that's up to you, but not expected.