Interesting; the general consensus seems to be that nylon strings require a much more precise technique, and that the benefit usually goes to the opposite side.
You mention non-standard fingerings and difficult stretches. If you encounter them much more often on the dark side than on CG, and play/practice them without the apprehension that might accompany them in repertoire where they are indeed not common, then yeah, I'd expect that experience to carry over.
There's another, similar effect that may be at play: that of taking a break. I remember wondering with fellow violinists, long ago, how you could have passages over which you just kept stumbling, always at the same place. Then you'd go on a trip for a couple of weeks without touching an instrument at all, and then upon your return that passage would just play itself perfectly. For a while at least, because I think there's a bit of euphoria involved.
Gretsch G9240 "Alligator" wood-body resonator converted to non-metal strings (China, 2018?)
Bolink baroque violin (Hilversum, 1982)
Formerly: Brian Cohen baroque violin (London, 1985), Nadegini modern violin (Paris, 1924)