Look, it's not a question of semantics as the meaning of the words fail/success is pretty cut and dry. It's also not a subjective argument because success/failure means the same thing to everyone to varying degrees.
So the question is: Is something that happens that your don't want to happen, even if that thing is good, still something that you didn't want to happen?
The answer is of course yes, because you didn't want that to happen.
So, failing to fail is a failure.
There is no logical way it can be interpreted as anything else.