If the French Navy really did confuse their own tests in the Mediterranean with the AF447 results, everyone involved would have had to overlook a difference in depth of several thousand feet, no, and of many degrees of longitude in all the locations? It's not even as if it's an obvious sort of mistake like a reciprocal or a decimal point error. Also, rather than providing "une zone qui n'etait pas la bonne", it would surely have provided invalid data.
I find this story unconvincing, and suspect the validity of Le Fig's source.