There is a species of error in the new church that teaches people can be saved outside the Catholic Church (denial of EENS).
This heresy of soteriology is related to the heresy of a new ecclesiology as taught by Vatican II (the Church of Christ "subsists in" the Catholic Church)

The error goes like this,

error #1) "An Orthodox who is invincibly ignorant that the Catholic Church is the true Church and he must be a member of It, can be saved if he  believes in the principle mysteries of faith, keeps the natural law, and dies with perfect contrition for his sins and intends (desires) to do all he must do in order to be saved - he is not saved because of his false religion, but in spite of it - he is saved by the Catholic Church and belongs to the Catholic Church by desire."

Now, how is this ^^^ heresy any different than imagining that one can innocently submit to a HERETICAL magisterium for their formal motive of faith while still retaining Church membership?

The same error is displayed concerning current Church membership during the crisis, it goes like this,

error #2) "A N.O. Catholic who is in ignorance that the N.O. church is a false church that is run by a HERETICAL magisterium and whom they submit to as their formal motive of faith - but do NOT submit to the heresies formally of the false magisterium they claim to be under - can be a member of the Church because they intend to be submitted to the true magisterium (which is currently eclipsed, missing, impounded, etc.)

So, you end up with.

1) The Orthodox would belong to the Catholic Church if he knew he had to - he has the intention to do all that he is currently ignorant of that is necessary to save his soul.

Compared similarly to,

2) The N.O. Catholic would get out of the false church and repudiate it, if he knew he had to - he intends to do all that is necessary to save his soul if God illuminated him to the trap of the false church.

Aren't both these errors above, at their root, similar?

IMO they are both based on the subjective intentions of the individuals concerned and not on their objective membership in the Catholic Church.

They both intend to be subject to the true authority of the true Church - that is their formal motive - but they are both objectively wrong about,
A) what the true Church is and
B) who is Its true authority.

2 individuals who both have the subjective intention correct, but the objective reality wrong. 
What is the difference in essence between error #1 & #2?

I am generally interested in what others think.

Thanks.