Hello Josias,
For the reference manuals, you can generate them by changing lng from 2 to 1 in doc_telemac.py (run doc_telemac.py --reference and you should have every reference manual in French, at least TELEMAC-2D one by running doc_telemac.py --reference -m telemac2d, I have just tried).
There are some old user manuals written in French but for quite old releases, you can find a few here (manuels utilisateurs de TELEMAC-2D, TELEMAC-3D, perhaps ARTEMIS):
www.opentelemac.org/index.php/manuals
Anyway, as for old releases, you will miss:
- new features,
- corrections of mistakes,
- addings to help users.
So beware, it may help you to understand basic and old features, but you may read wrong or deprecated things inside.
That is why I would strongly recommend you to read the latest manuals available with the latest release (v8p4r0).
Hope this helps,
Chi-Tuan