Thanks for your fast answers. I don't remember if the civ4 CD has only the main installation language of the country where it was bought or if we can pick an other one during installation... anyone knows ? I think so as reading you 3Miro.
By the way, is there any french guy in the RFC team ? If I can set my game in english and if RFC Europe works for me, I should help you for translation. But as you can see, I'm not so fluent in english writing and, unfortunately, I know badly XML (I try to learn modding alone... it's kinda hard).