Our parish did this, too. I find it VERY diffucult to sing and I’m a trained musician.
Jennifer
Yes, my newly former parish does this Missa Emmanuel as well. (We were just granted permission to register at our Cathedral which we’ve been attending for about 8 years and have been part of.)
I never heard of it until this year when I had volunteered to cantor at my former parish. It’s ok to sing for me, but I’m trained and a professional musician, but for the congregation, I found that they have a hard time singing it. The Sanctus especially. That parish is a real singing parish, too, so it’s not because they just don’t sing. Sometimes they bring down the house with their singing.
The problem with it is the way the text is set to the music. It feels forced - sort of like trying to squeeze yourself into a size 0/2 when you are a 4/6.

You can get it up around the hips, but it’s a bit too snug and won’t zipper up all the way. It just doesn’t look or feel quite right. That’s how the text setting feels with me.
Actually, one of the priests at that parish got into a really hot discussion with the other priests and the music director about it, saying that as long as he is saying mass, never to have that Missa Emmanuel played.
I love the melody for the Veni, Veni, but not for the mass parts. It’s just doesn’t work IMO.