That enclyclical did nothing to curtail Hitler. All it did was to cushion the Roman Catholic schools and churches in Italy.
And a declared excommunication would have had no more positive impacts—the point had already been made.
Of course, Pacelli had read Mein Kampf—how else would he had counselled Pius XI to write the encyclical to which I linked in post 50—but I don’t suppose you read that either.
I've read plenty of RC propaganda. The fact is Pacelli enabled Hitler and the Nazis to destroy the Jews by dismantling the final opposition to Hitler in Germany.
With "friends" like that, who needs enemies?
The majority of Hitler's coterie were practicing Roman Catholics.
And thus, none of them has been excommunicated.