Duuh, sometimes the best ideas only hit me in the heat of the battle. Did Utsuho's last Spellcard in 12.3 by standing at the edge of the screen, shooting in time to hit the black ones, which did not always go particularly well. As I was torn to shreds, wondering if this Spellcard really was supposed to be that way, certain doom if you mess up even once, that is, I suddenly realized that I can just graze around in the middle which also makes shotgunning it so much easier.
Sanae's shotgunning capabilities are also a major derp though, only realized that you can absolutely destroy pretty much anything that floats by shotgunning it when I was figuring out strategies for Utsuho's penultimate Spellcard. In retrospective, doing certain Spellcards without shotgunning looks kind of funny now.
I have to say, it really did help to get used to Sanae, I'm actually starting to like her controls now.