You should always aim to work with a translator who is a native speaker of the target language (the language you need to translate into), so if you need to have your English content translated into French, using a native French translator is the way to go.
Although I consider myself bilingual and bicultural after living in the UK for 17 years, I only translate professionally into French, my mother tongue. As confident as I am with my English skills, I am fully aware that I still make mistakes which I wouldn't do in French - there are probably some sentences in this post which might sound slightly awkward to a native English speaker.
However, being a native speaker is not enough to be a successful translator. As well as knowing their source language(s) extremely well and having a ton of other skills (which I will explore in other posts), translators should be proficient linguists and writers in their native laguage.
✅ have an excellent knowledge of grammar and spelling rules.
✅ have a very wide vocabulary and produce authentic, fluent translations.
✅ be able to adapt their writing style to the type of text and tone of voice they are working with.
✅ be creative and able to come up with inventive solutions to tricky source content.
✅ read a lot and stay up-to-date with their native language.
Unfortunately, being a skilled linguist in your mother tongue is not a given and requires training and practice, so dig a bit deeper:
What level of education does your translator have in their native language? Have they used it on a professional level? Have they studied translation using both their native and foreign languages? Do they have a portfolio of translation work showing their writing skills in their native language?
Feel free to check out the “About Me” page on my website (link in the first comment) to see how I have developed and used my French language skills professionally throughout the years, from studying for a language degree in France, qualifying as a French teacher and teaching in the UK for 10 years, to translating professionally into French for the past 7 years and becoming a Chartered Linguist.