The game port created by Kweepa makes extensive use of the original text stored in the strings.pak file. Therefore, replacing this file in the data directory with the French version should be enough to translate the dialogue, item names, and subtitles for the intro movie.
Unfortunately, as Kweepa mentioned, the subtitles for the remaining cutscenes are stored in Unity asset files. They can be translated using UABEAvalonia.
The interface text, on the other hand, is embedded in the Assembly-CSharp.dll file. Editing it is possible, but requires export and import scripts built using the dnlib.dll library.
I prepared the Polish version this way, and everything seems to be working.
It should also be noted that the game was not designed with languages other than English in mind. Some sentences are assembled from individual words, which may cause issues with correct declension and conjugation.
Kweepa, I love this port. Everything is perfect-the UI, graphics, and controls.