(yes, I know I'm a few days late with this but I was just reading another blog and this issue was pointed out...)
that while it is still unclear whether permission will be given to teach/use/practice musical settings of the Mass Ordinary, the first time that the congregation will be singing the GLORIA in the new translation will be (besides Immaculate Conception,) CHRISTMAS EVE! So, you're not exactly going to be teaching music to the congregation before Mass on that day.... but the congregation at St. P won't care, because they already know it in Latin! :-)
so I'm delighted that mine and Fr. G's efforts to introduce various Latin parts of the Mass to the people, and planning ahead!, will truly pay off, since for every part that they sing in Latin, they will notice one less immediate "change!"