AFAIK, all post-WWII Schneider lenses are at least single coated. (Perhaps a very few exceptions on the resumption of production post war ???) Early ones have a triangle symbol to advertise this feature. The triangle symbol was dropped after a few years, by which time single coating was universal and featuring it was no longer a selling point.
I was researching a 180mm symmar-S (a generation after the convertibles,) and Chris Perez's comparison site listed 2 lenses, both Symmar-S, one was MC and the other was single-coated. The resolution of the single (1970) was well above the MC version,(1980) FWIW. David O'Connor