Very interesting analysis, it has some legs.
Jasenovac was up and running a full year before Auschwitz was built, and even before The Final Solution for the Jews was fully developed.
Pope Pius XII had the opportunity to speak out against the practice of genocide when the victims were primarily Serbs and Gypsies, and it would have not been a criticism of Hitler because the perpetrators were Croats, not Germans. As a matter of fact, Hitler didn't like the Croat genocide of Serbs because it was creating even greater resistance to the Germans by the Serbs outside Croatia.Instead, the Vatican described the mass slaughter of Serbs by the Ustase as "teething pains of a new state".
By the time that the Final Solution got under way, it was too late. If Pope Pius didn't speak up for his fellow Christians being slaughtered in the name of the Catholic Church, he wasn't going to speak up for the Jews being murdered by Hitler.