"...make certain that his new film on the last 12 hours in the life of Christ does not portray the Jews as collectively responsible for the crucifixion."
Considering the Abrahamic, Davidic, and Mosaic Covenants, it need to be well noted that the Jews did reject Jesus as Christ. The New Covenant now provides for all men, Jew and Gentile alike.
Perhaps it is better to say the Jews of the day, especially the Sanhedrin were fully liable for the death of Jesus Christ. Christ allowed himself to be taken and crucified by remaining obedient to the Father. Nevertheless, it was indeed the Jews who offered that sacrifice.
Perhaps this best exemplifies the protocol of proper sacrifice. Jesus held the royal title as the high priest and offered the Perfect Lamb remaining faithful and obedient to the Father. The active slaughter of the Lamb came at the hands of man, and just as liable as the centurions or Pilate, were those who were afforded the opportunity to allow Jesus, the Christ, to be released and instead chose Barrabas.
The holding of court at night to decide a capital charge by the Jewish authorities obviously was intentional as was the tone of accusation against Jesus from the last Supper onwards through the Ressurection.
If the meaning of Vatican II doesn't match the implication, then perhaps Gibson's film will help to clarify the issue.