Liturgical Date Problems in Sermons for All the Sundays in the Year by St. Alphonsus Liguori

Liguori, Alphonsus M. Sermons for All the Sundays in the Year. Translated by Nicholas Callan. Eighth Edition. Dublin; London: James Duffy & Sons, 1882.

This work has strange liturgical date tagging:

1. I find in it things like "Epiphany Season 6 Sun A", which seems to suppose a "Year A", and also things like "Trinity Sunday A", which push in the same direction. Yet there was no "Year A" in any liturgical system St. Alphonsus could possibly have used.
2. The 22nd Sunday after Pentecost gets "Proper 22 Sun A", which continues with this strange "A" nonsense and includes the word "Proper" for some unknown reason.* This applies, mutatis mutandis, to the rest of Sundays after Pentecost as well.
3. And then sermons for important liturgical dates like Quinquagesima,  Septuagesima, Passion Sunday (aka the Fifth Sunday of Lent), Pentecost, and even EASTER have no liturgical date at all.
4. The First Sunday after Easter gets no liturgical date; the reason for this becomes apparent when the Second Sunday after Easter gets a label seemingly indicating that it is the Second Sunday of Easter, which it is not. This error continues, mutatis mutandis, thereafter.
5. Eventually, the 6th Sunday after Easter (mistakenly called the 6th Sunday after Pentecost in the text itself) is mislabeled as "Ascension A", when, for St. Alphonsus, it was not the Ascension but the Sunday within the Octave thereof, i.e., the Seventh Sunday of Easter (or the 6th after Easter).

What's going on, and, more importantly, can it be fixed?

*Consulting the Info page, I see that its liturgical dates are taking from the 1979 BCP's Liturgical Calendar. Oops.