The brazing should never be the point of failure. Peeling back like that is pretty rare it's so bad. There are a couple of reasons why that might happen. Cleanliness or overheat. I was a little shocked when I saw the pictures of the waterford workshop when they had their auction. So cleanliness isn't out of the question.

Hard to tell from here, but it looks like they just flowed silver around the outside of that tang. I have a theory about how that happened. The first time I brazed some stainless dropout axle reinforcements, I overheated it and the silver wouldn't flow at all. That was a mess to clean up. Of course, it was immediately obvious to me that I only had silver around the outside. I feel like the waterford worker should have known that was happening. I have done a lot of stainless since then, but only one stainless fork crown. It was a non-event. It is really easy to overheat stainless, it takes about the same amount of heat to get up to temp as regular steel, but at the end it goes from not hot enough to overheated really quickly.