"He says they want livestock and grain."
The Romans increasingly attached interpreters to government commands as their empire expanded, and in the spirit of the dual-use functions of the Roman Legions, specialist soldiers used as interpreters.
There was a certain level of privileging of Latin - even Republican/Imperial magistrates who could speak barbarian tongues were expected to use interpreters for official business, to emphasize just who the magistrate was speaking for (the ROMAN PEOPLE, of course!)