I've watched several of the french shows online, and unless the stream or audio was very poor when it was said, it was not said. The "f" word in question rhymes with duck. I don't see how Disney would allow the Muppets to swear reguardless of language or if its culturally acceptable. The Muppets are the Muppets, even if the show was at a later time period, you know that some parents/guardians would allow their children to watch, or even tape the shows to watch at a different time. As well, if in fact the Muppets were swearing, don't you think that other media outlets would have picked up on this? Disney has an image to protect, reguardless of which property is being used.
I've also noticed that a lot more media outlets (online, tv, radio, etc), have picked up the fact that this pilot is (hopefully) out and about with the suits at Disney. Hopefully this buzz will have a postive impact. *crossing fingers*