In the past I have needed to translate critical material. When using casual translators, the standard is that
you have both forward an back translation. In other words have one group translate from your language to French
and have another group translate the French back to your language. Then resolve the differences.
This is probably overkill for you app, but I am just saying...
P.S. In theory, this technique also works with machine translators - but resolution of differences between AI's is problematic.
P.S.S. French certainly has more 'nuance' than English