tbm: Are you saying that Leica lenses, used stopped down, will not produce "stars" from blown-out in-scene light sources? I have some difficulty believing this.
If coating deficiencies were to blame for "stars" I wouldn't be able to suppress them so easily by shooting my single-coated old Mamiyas wide open. Flare is most assuredly coating (and surface count) related, but that's not what's under discussion--"stars" are. They can't be fixed with good coating, good film, good developer or even a shamrock in your pocket. They're an aperture phenomenon, period.