1) The Council, while recognizing X as Pope, meets and call the Pope into a trial to explain his heresies, to admonish him. If he retracts he continues to be Pope, if he doesn`t retract then he ceases to be Pope.
Review the case of John XXII. They didn't call him to trial, yet that did not prevent them from determining amongst themselves what were the facts of the case and the nature of the offensive statement. They didn't pretend to canonically admonish him, but certainly he was admonished outside of his capacity as Pope. Those in authority who might ascertain that such a statement was
certainly heretical and the ostensible man who occupied the office of the papacy persisted in his private capacity to maintain the proposition, it would consequently be determined that he did not desire to hold the Catholic faith any longer. At that point, if he persisted in maintaining his office, refusing to leave the Church, my opinion is that he would require to be forcefully removed from his office.
The case of tacit resignation entails a certain evident nature, such as a priest marrying. But we are not dealing with your average heretic here my friend, your mere say so doesn't make it so. One of the most notable features is their distinct unwillingness to pertinaciously adhere to anything at all that could be construed as heretical. But the sede hasn't really left first base until he can determine with certitude that a proposition is heretical. What if these men don't deal in propositions at all, but use their imaginations as a way to theologize? What if they employ a false mysticism or philosophy in an attempt to explain the faith? What of mere theological errors? Have you ever studied their writings? The manner in which they speak? We are dealing with a different animal here.
2) The council, while considering him no longer Pope, meets and call the Pope into a trial to explain his heresies.
Was this knowledge simultaneously infused into their minds? Did they have no contact with the Pope to ascertain what he meant by a proposition? Have you had recourse to the Pope to ascertain what he meant by a controversial statement?
3) If I`m not mistaken you accept the possibility X ceases to be Pope but the fact of the declaration belongs to the council. Now let`s suppose this happens and X is called into trial and the council says: "X is not guilty" (since the council is not infallible is it?). So what will happen? X will suddenly be Pope again? Was always Pope? Will not be Pope and the Church will accept him as such...? What?
As I said, they wouldn't attempt to "call him into trial." But that doesn't negate the possibility that the facts be ascertained without first necessarily denying he is Pope. That is an absurd procedure.
You're simply not allowing anything between total inaction and formal canonical proceedings.
Really, this restricting of the matter to a single Pope is irrelevant. The sede has a much larger problem to deal with regarding the very divine constitution of the Church. It is impossible, except by force of will, to restrict this question to a single line of Popes. Logic and consistency necessitates this judgment be applied to all cardinals, bishops and priests of the novus ordo who accept these "heresies" in short, the entire juridical structure of the Church, devoid of ordinary jurisdiction. A but Christ's Church has possessed and will always possess ordinary jurisdiction, otherwise it would be impotent to fulfull its mission, it would become something it was not before, it would simply vanish and become one sect among many. Unless you assert that traditional priests and bishops form this juridical structure, a formally separate Church, with its nature perfectly remaining, then you've got a serious problem on your hands.