This looks great! I look forward to hearing it!
According to interviews with Bernard Fèvre, Giordano served as producer with L'Illustration Musicale. One could/should take this with a pinch of salt, of course, but some sources claim that the co-writing credit for the "Black Devil" LP was only added to recoup an investment in the project - though it seems more likely he served as lyricist. He seems to have been something of a sketchy character, particularly in his later years, and he is widely reported as having been arrested for fraud in 2007, one newspaper article mentioning him as a "repeat offender".
He was undoubtedly a brilliant composer, keyboardist and producer, though!
I don't know anything more about her, unfortunately, but in addition to Henri Giordano, Anne-Marie Olivier, who has a writing credit on Musax 100.007, seems to be related to the Giordano brothers, later taking the name Anne-Marie Giordano. A spouse, perhaps?