Is the criticism of Pius XII for not speaking out against Hitler during World War II merited?

No, I do not think it is merited. What more was the pope going to do? He helped Jews escape, he said what Germany was doing was not right, but that is never enough for the pro-Jewish side of that debate; you always have to do more, and then they still complain. He was Pope from 1939 to 1958, right in the midst of it all. In 1946, the year after the war, the Jewish author Jules Isaac wrote a book, Jesus and Israel, in which for the first time in history a Jewish author accused the Catholic Church of being anti-Semitic, and not only the Church but the Fathers, particularly Chrysostom and Augustine, and even the New Testament, particularly Matthew and John. That was the theological climate. Isaac is typical of an approach that never looks at the sins of Israel as a reason for its troubles, but always looks for someone else to blame. On top of that, in 1943 Pius XII allowed Catholics to study liberal Protestant interpretation of the Bible, which taught that only what is spiritual or salvation-oriented in Scripture is inspired, if any of it is inspired at all. Once Catholic scholars adopted that, they could agree with Isaac that second- or third-generation Christians filled the New Testament with anti-Semitic statements. So in a sense Pius XII opened the door to the very reinterpretation of Scripture that now feeds the accusations against him. No matter what he did, they would have complained, and they are still complaining today.