Wow, thanks for your quick and helpful answers! I did know about the Wayback machine "trick" but I didn't think of it this time, silly of me.
I've checked in French libraries specialized in cinema studies and they don't have this issue either. But now that I've got the writer/interviewer's name I will try to reach him directly, I think it's my best best.
Thanks also for the thread mentioning this interview, it was actually one of my sources but I can't use the Kasdan anecdote unless I'm 100% sure that this specific quote was from him, and as you saw in the thread, it sounds more like some interpretation than an actual quote.