So, in your opinion, it does not really matter if any holiness still exists in the conciliar church, since heretics reign there, and we can't be in communion with heretics? I'm just trying to clarify your position.

Never fear.  Jupiter is here.

See, it's OK for YOU to "interpret" papal teaching and then declare your conclusions dogmatic, but not for the sedevacantists, eh?  This is talking about the ESSENTIAL perpetuity and visibility of the Holy See. 

We know that a prolonged vacancy of the Holy See is possible, and that too contradicts your interpretation of this teaching.

As for your second issue, I've repeatedly argued that there can be and are people who are formally Catholic who are nevertheless materially divided due to the Crisis.  This is the second time now that you've straw-manned me with the arguments of the dogmatic sedevacantists, which I have consistently opposed.  In fact, I argue that there are some bishops in the Church who continue to exercise ordinary jurisdiction.

Grace is most assuredly the primary vehicle and the starting point: Without it, man cannot assent to the supernatural truths of revelation.

The fact that Protestants can be deluded is as irrelevant to that article of faith, as that men can refuse it.

It is the starting point, but not the vehicle.

The Council of Trent (Sess. VI, cap. vi, and can. xii) decrees that not the fiduciary faith, but a real mental act of faith, consisting of a firm belief in all revealed truths makes up the faith of justification and the "beginning, foundation, and source" (loc. cit., cap. viii) of justification.

“The Synod furthermore declares, that in adults, the beginning of the said Justification is to be derived from the prevenient grace of God, through Jesus Christ, that is to say, from His vocation, whereby, without any merits existing on their parts, they are called; that so they, who by sins were alienated from God, may be disposed through His quickening and assisting grace, to convert themselves to their own justification, by freely assenting to and co-operating with that said grace: in such sort that, while God touches the heart of man by the illumination of the Holy Ghost, neither is man himself utterly without doing anything while he receives that inspiration, forasmuch as he is also able to reject it; yet is he not able, by his own free will, without the grace of God, to move himself unto justice in His sight. Whence, when it is said in the sacred writings: Turn ye to me, and I will turn to you, we are admonished of our liberty; and when we answer; Convert us, O Lord, to thee, and we shall be converted, we confess that we are prevented by the grace of God.”

The fact that people can be deluded in matters of faith or outright reject Grace is known to man by faith which is known by his mind and ability to reason which is the most relevant part of this discussion.

The longest vacancy of the Holy See has been less than three years, ...

This is not an opinion. It is a matter of fact that heretics reign in the material structures of the Church and where there is heresy there is no holiness, regardless of appearances. The Arians were known for their penances, prayers, zeal, and good works but it availed them for naught since they had no faith on account of their one single heresy.

Also, yes, madame, a Catholic cannot be in communion with a heretic by divine law.

You have absolutely no theologian that supports your case while we have the following:

A. Institutiones Theologiae Fundamentalis [1929], Rev. A. Dorsch
— “The Church therefore is a society that is essentially monarchical. But this does not prevent the Church, for a short time after the death of a pope, or even for many years, from remaining deprived of her head [vel etiam per plures annos capite suo destituta manet].”