So rather than arguing that an infallible magisterium is not necessary to recognize and establish writings as Scripture, which you cannot, you presume that the alternative is "sola individualistica" (if there is such a word)?"
This is misleading as as SS disallows claiming assured infallibility, so that neither the individual nor the council are the supreme authority. It was by manifestation of the truth that a general consensus saw writings established as Scripture before there ever was a church in Rome, and which writings the church relied upon. And it is by "manifestation of the truth" (2Cor. 4:2) that the claim to be the church of the living (not dead) God continues to be established.
And yet all individuals, including Catholics, choose what they will believe from pastors, and engage in some interpretation. For they individually first choose to submit to Rome, and then to continue, and then often must engage in some interpretation of what is taught, and what magisterial level a teaching falls under, and thus what degree of assent is required. In addition, your last pope taught that “over the pope as the expression of the binding claim of ecclesiastical authority there still stands one’s own conscience, which must be obeyed before all else..,” even it is not an autonomous and exclusive authority for deciding the truth of a doctrine.
However, under Rome is where "sola individualistica" is supremely manifest, if the pope is not subject to ecumenical council as most Roman Catholics (Bellarmine, etc.) hold, and Dictatus Papae and other teaching affirms (thus no council, not even an Ecumenical one — which he must call and approve — has authority to depose a Pope against his will). Others hold that he is subject to councils, for his “relation is one of neither superiority nor inferiority, but of "intrinsic cohesion."
The pope did not make that comment outside the context of Gaudium et Specs or the Catechism. In all cases our consciences must be properly formed to be reliable.
CCC 1783 Conscience must be informed and moral judgment enlightened. A well-formed conscience is upright and truthful. It formulates its judgments according to reason, in conformity with the true good willed by the wisdom of the Creator. The education of conscience is indispensable for human beings who are subjected to negative influences and tempted by sin to prefer their own judgment and to reject authoritative teachings.
CCC 1784 The education of the conscience is a lifelong task. From the earliest years, it awakens the child to the knowledge and practice of the interior law recognized by conscience. Prudent education teaches virtue; it prevents or cures fear, selfishness and pride, resentment arising from guilt, and feelings of complacency, born of human weakness and faults. The education of the conscience guarantees freedom and engenders peace of heart.
CCC 1785 In the formation of conscience the Word of God is the light for our path, we must assimilate it in faith and prayer and put it into practice. We must also examine our conscience before the Lord's Cross. We are assisted by the gifts of the Holy Spirit, aided by the witness or advice of others and guided by the authoritative teaching of the Church.
CCC 1786 Faced with a moral choice, conscience can make either a right judgment in accordance with reason and the divine law or, on the contrary, an erroneous judgment that departs from them.
CCC 1787 Man is sometimes confronted by situations that make moral judgments less assured and decision difficult. But he must always seriously seek what is right and good and discern the will of God expressed in divine law.
CCC 1788 To this purpose, man strives to interpret the data of experience and the signs of the times assisted by the virtue of prudence, by the advice of competent people, and by the help of the Holy Spirit and his gifts.
Peace be with you
” your last pope taught that “over the pope as the expression of the binding claim of ecclesiastical authority there still stands one’s own conscience, which must be obeyed before all else..,””
Well, Benedict was always a much sharper theologian than most of the RC apologists around here!