Kirsten I hope Luna has managed to shift the hairball and is now feeling much better.
Colette doe s fair bit of liquid vomiting and eats lots of grass - but she's contantly grooming Cleo as a sort of comfort thing I think, so she's hard at work with that tongue and needs to get rid of it somehow. She's always been a "chucker"
Since I started feeding her Hills Science diet Furball Senior dry food some time ago (alongside her usual wet) she has been coping much better.
I haven't seen the wet (canned) version, but then as it's vet-supplied I haven't asked, didn't know about it.
The other thing and I'm sure you know this, is a little olive oil or similar mixed into the food?

Hope you're feeling better Luna!