Curiously, my Stronglight catalog (pg 7) shows this cartridge as being supplied in French, English, and Italian thread:
http://www.os2.dhs.org/~john/catalogs/stronglight.pdf
And FWIW, I have a similar Pino Moroni cartridge BB that is RH English thread all the way across:
Needless to say, I've yet to find a frame that works with it...