In the future, I suggest that you make plans for an English-speaking person to travel with them. Or, on the other hand, just book on a MAJOR airline. All major carriers (who fly internationally) have access to 24-hour translators via telephone who can assist in translating for non-English speaking passengers.

In addition to booking on a major carrier, please have the check-in agent note the record that they are non-English speakers (and which language(s) they speak). Again, a major carrier will do this for you.

AirTran is a low cost airline with low paid employees who apparently didn't care about your parents.