Khedira actually bothered to do his presentation 2 years ago in italian despite not knowing the language, dedicated enough just to memorize what he should say to introduce himself for couple minutes. That does not sound like someone who would not learn the language after 2 seasons. He's clearly betteer with english tho, and seems like quite the diplomat, so wouldnt be suprised if he is one of the few used as the vocal english speaker promotion wise (seems to be heavy user of social media too).