So my friend and I are having a small argument on what that means. I have never seen a gild fail period. I am under the impression that having a gilding fail means you don't get a new slot.
He is under the impression that if you fail a gilding you get nothing out of it.
Namely we were looking at the Tailoring Credo and its final level "The first gilding of a new artifact is always successful." I think this means you will always get a second gilding slot he thinks it means that you will never fail at putting a gilding on the item.