It's extremely hard to make translation across sci-fi species some of which don't even use acoustic languages (chemical, signs, electric). So, usually unless the two species are in long-term relations it's very problematic.

There was a "big invention" and the "biggest mystery" - unlike bodies, brains of different species operate in extremely similar way. So, a "xenolinguistic module" was invented to aid interpreters, especially in establishing first contact. Installing such a thing is a crippling experience, literally installing a big device in one's brain. It's capable of "copying" electromagnetic state of another individual's brain and projecting it onto wearer's brain. It's far from mind reading and needs the other party to cooperate.

An experienced linguist can start making sense of those signals after some time, having an "acoustic language" for reference is a huge bonus. There was a huge deal establishing contact with vegetos - sapient trees who used chemical language. Thess linguist could not get a proper reference and therefore the "link" has finally been established with mediator kerf who use both acoustic and chemical language. Just to find out that vegetos are capable of acoustic speech, though were never using it for communication between each other.