As to Count V.
V. It is false that the only sexual acts that are good of their kind and morally licit are acts between husband and wife.
– Open Letter to Bishops of the Catholic Church, Easter Week, 2019
In FUNDAMENTALS OF CATHOLIC DOGMA, there are no De fide dogmas that are relevant to this count.
CCC 2349 “People should cultivate [chastity] in the way that is suited to their state of life. Some profess virginity or consecrated celibacy which enables them to give themselves to God alone with an undivided heart in a remarkable manner. Others live in the way prescribed for all by the moral law, whether they are married or single.” Married people are called to live conjugal chastity; others practice chastity in continence:
There are three forms of the virtue of chastity: the first is that of spouses, the second that of widows, and the third that of virgins. We do not praise any one of them to the exclusion of the others. . . . This is what makes for the richness of the discipline of the Church.
Therefore, Count V. is a false proposition (propositio falsa), a proposition contrary to a dogmatic fact which in this case is ‘others [other than married couples] practice chastity in continence’.