Francis is being very clear.  The Argentineans got the point, and a pastoral word of encouragement.  The four cardinals were not asking questions.  They were making their own point.  To give an answer, Francis would have to repeat himself.  And he did make the same points in his Apostolic Letter "Misericordia Miseria" at the close of the Jubilee Year of Mercy.

St. John Paul II made much the same point by the examples he gave in FC 84.  If you look at indissolubility as an absolute independent of such examples, you risk violating the greatest of the commandments, the source of "all the law and the prophets."  Francis is simply pointing out that in cases like the examples in FC 84 discernment -- where the person seeks submission to the Spirit of Christ -- is necessary to assure that the greatest of the commandments is followed.  The role of the pastor is not permission.  In the end, the person must answer to God, who is written on the human heart.