Is this really a matter of prudential judgment or just another reflection of the false ecumenism (aka Kumbaya-ism) of Vatican II?
It is a matter of mistaken prudential judgment as was "ecumenism" generally and the Kumbaya nonsense for mental defectives and Bishops Trautman of Erie and Imesch of Joliet and the unlamented Bernardin and Law and McPhony.
Truly Magisterial statements are relatively rare. Embarrassing faulty prudential judgments happen frequently.
True "ecumenism" occurs when Russell Kirk became a Catholic late in life and Friedrich von Hayek and many Anglican clergy eager to swim the Tiber to flee some of the shenanigans in that denomination. It might also occur if Ted Kennedy had become a formal devil worshiper or other analogous developments.
In it she explains how she had her nuns read Vatican II thoroughly -- and what they found changed EWTN.
They found that Vatican II endorsed the Latin Mass -- so Mother changed her programming.
I do think that the US Bishops did not interpret it correctly, but went their own wayward way.