Sir Bobby Robson spent a good deal of his management career at Sporting Lisbon, Porto, and Barca without speaking Portuguese or Spanish. You might have heard of his translator--Jose Mourinho.
Giovanni Trapattoni manages the Republic of Ireland national team (and is one of the highest paid international managers around) speaks notoriously poor english. When he managed previously in Germany, he was also known for mangling the local tongue.
Jose Mourinho is a fascinating character. He is highly educated and speaks 5 or 6 languages fluently. He is one of the most tactically astute managers in the modern game. He's also notoriously paranoid, convinced everything is a conspiracy against him, which seems to stem from an incident in his childhood where an uncle was a wealthy member of the ruling elite, but a peaceful coup meant that the family lost a lot of their wealth. Here's a good documentary covering his recent managerial career:
