I'd be hoping to get some input from people who actually know about paint chemistry...
The fact is that the paint seems perfectly fine, after ~10 years, when applied onto small areas without the hardener.
It is apparently just as good as the original Socata paint, which while generally very well done has been known to peel off rather easily in large strips, leaving behind just the green primer. This happens around the filler caps, where careless refuellers tend to chip it. One assumes that they sometimes applied it under conditions of temperature or humidity which were outside the painting spec.