I basically just googled French Pokémon “DP55” and looked through the six pages of results. 
I either came across old eBay sold listings (through backups/caches of other websites) or the French links I posted above (with some help from Google translate, since I can barely read French, haha).
And I knew there was a pretty big German Pokémon wiki which contains more information about certain German releases than Bulbapedia, so I had hoped that French wiki would too, but unfortunately it was rather lackluster… 
Oh, that’s a nice find! Thanks for sharing.
And didn’t think about Belgium, but I guess that’s indeed a possibility too. Belgium releases are usually in French, and sometimes English.
I always like these kind of researches personally. Can also be seen with some of the articles written by me. 
It’s unfortunate I wasn’t able to find any useful information, though. Bit of a bummer.
Greetz,
Quuador