As a native speaker of English I only translate into my mother tongue in order to provide translations of consistently high quality.
Translators translate the written word, interpreters interpret the spoken word.
The source language is what a translator translates from, and the target language is what they translate into.
You can see my name on page 37 of the official list published by the French Court of Cassation: http://www.courdecassation.fr/IMG///Liste_Expert_CA_StDenis_2015.pdf. For information, any certified translation carried out by a French court-sworn translator is valid all over France and with foreign authorities.