The threshold is what was defined at Vatican I. There are no other requirements. As was explained by the Relator at the Council, if the Pontiff is negligent in his duties and does not investigate thoroughly enough, the Holy Spirit will either prevent him from proceeding to a definition or cause the definition to nevertheless be correct. If a definition is binding on the universal Church, made in virtue of the papal authority, and concerns faith and morals, it is infallible. Period. Furthermore, it's not up to the faithful to decide what "concerns faith and morals":
It is also up to the Church to decide how far her infallibility extends: otherwise there could never be any certainty as to whether, in defining something, she had transgressed the limits of her magisterium. In that case infallibility would be placed in grave peril, and the whole of religion would turn out to be placed in doubt. From this it follows that, if the Church declares that something pertains to her magisterium, or proposes it as requiring the assent of faith (credendum), such a decree is to be held as infallible. (J.M. Hervé, Manuale Theologiae Dogmaticae, Paris, Berche & Pagis, 1935, vol. I, p. 507)
You're confusing the issue. I explained it for you. I wish you would take the time to read this:
Yes, but I'm trying to get you to admit that there IS a limit, a threshold. And what I'm saying is that what those fathers were talking about is a threshold, a process, that doesn't now exist. How the Church declares a Saint meant something different to them, in other words, than it does to the pretenders, today. The same fathers, for example, would speak of the Greek as controlling in translations. But they meant a particular version, one reliable, and later lost. You have to understand their specific reference, or you can easily abuse their words.