Not necessarily. Being a Roman administrator, Pilate would know Latin and Greek without question. Latin was the legal language of the empire (and commonly spoken in the oldest parts of the empire), and Greek was the common language of the rest of the empire. Alexander the Great and his successors forced territories they conquered to speak Greek. When the Romans took over their territories (piece-by-piece), they left Greek as the language since so many people used it.
The Jews would know Greek as it was required for commerce with anyone from the west. Greek was the lingua franca. Jon gives excellent reasons for the people to know Greek, Aramaic, and Hebrew. I give more for Hebrew.
As far as the "what I have written" statement, having subordinates do it counted as doing it yourself. For example, Joseph of Arimethea, by all understanding an old man took Jesus' body
Matthew 27:60 and placed it in his own new tomb that he had cut in the rock.
Clearly, he did not carve it himself. Likewise, David did not single-handedly slay ten thousands. Nor did David drive home the sword which killed Uriah. But because David ordered it done, the guilt was his.
2 Samuel 12:9 ...You have struck down Uriah the Hittite with the sword and you have taken his wife as your own!
It would be unlikely for Pilate to know Hebrew as the Jews could speak Greek. However, it would not be impossible.