I'll be updating all the catalog files shortly, after which you can proceed to raise the PR for the French translation. Please check my email on "pgadmin-hackers" within the next half hour.
I would like to offer my participation to support the translation of the pgAdmin language files into French. I use pgAdmin every day for my work.
For your information, I know Fred Escallier very well. I worked in the same company for 5 years. Now he has changed jobs. He became a farmer in the French Alps. It was Fred who asked me to take over his work as a translator for pgAdmin.