That was just an example to illustrate the difference in Quality boost, even if it was always a “perfect succeed” (almost doubled in one occasion).
I did testing with level 52-53 items, too, and with 250 VIT I'm not noticing any difference in Quality boost in comparison to 212 VIT. Same for Weaver and Goldsmith with DEX.

About Craftsmanship and Magic Craftsmanship... Are you saying the first influence success rates and the second progress gain percentages? Did you notice a difference on this?
Because I already read this theory in the past, among the many others, but like I said I've a Craftsmanship Set and Magic Craftsmanship Set, that I created last year to focus only on one of those stats as I tried to understand them, giving me the highest boost; however I never noticed an improvement/difference in success rates with my over 150 Craftsmanship, for instance (always in comparison to crafting half-naked).

I think an official word from the devs is needed, they're the only stats without a proper explanation, after all (and also Control might need an update, for the reasons I explained in the first post).