Hi KitCat,
I'm not sure if these ideas are CRF friendly; but, I did have experience with probably in the top five of all-time finicky eaters, maybe even top three or four -- who, by the way, had special dispensation regarding a certain kind of no-no food from Dr. Lisa (for which and whom we were always grateful...)... And, no, it's not recent, yet it's permanently embedded in my memory bank and heart...
Parmesan cheese sprinkled over something more appropriate (thank you, Anne and French Fry, forever in our hearts). Apparently it adds an enticing stinky, bringing-them-to-the-bowl scent/flavor (which I can't verify because have no sense of smell, but, often worked for Giz!)...
Grilled chicken, steak (trust me, round steak will do), or pork chop. All high protein, low carb...
Cheese. Giz had a thing for extra sharp cheddar... Okay, and provolone... Swiss in a pinch...
I'm not even going to tell you the other stuff... Suffice it to say, that, one night I actually put out 11 plates, bowls, and saucers full of all kinds of food. Giz finally decided she liked the 11th menu item...
You're right, it's imperative your cat eats. You can go for the healthiest of diets; but, if she won't eat it, then just give her what she likes and will eat. You can work the insulin around it. Again, I'm not sure about the CRF factor...
I feel for you, dear KitCat, I really do. I fried more than one George Foreman grill on Gizzie's behalf... And, am amazed to this day, I don't have bald spots from pulling my hair out...
Love and countless hopeful hungry hugs for you and your furry girl,
Deb and Nikki -- and, Giz, forever whispering in my heart, and undoubtedly driving The Bridge's chef nuts...