For someone who translates languages:
* Translator
* Linguist
* Intermediary
* Go-between
* Mediator
* Facilitator
* Spokesperson
For someone who explains complex ideas:
* Explainer
* Clarifier
* Analyst
* Commentator
* Expositor
* Elucidator
For a computer program that converts code:
* Compiler
* Translator
* Parser
* Assembler
* Decompiler
For a person who interprets music:
* Performer
* Musician
* Conductor
* Soloist
* Ensemble
Choose the best synonym based on the specific meaning you want to convey.