When my FSIL got married 10 years ago, she sent out two sets of invitations, one in English and one in Vietnamese. My fiance says that we probably don't need to do the same, since the vast majority of his family speaks English. The only exception is his grandmother, who lives with English-speaking relatives. I, however, think that his sister set a precedent and we'll come off looking rude if we don't send out a Vietnamese version. It's really only his family we have language concerns about, as my family only speaks English.
If you were in my shoes, would you send out two sets of invites, send out English only, or combine the two languages on the same invite?