Mark, my Martha has been CRF for 2 years now and she's never had Fortekor - my vet doen't seem to prescribe it as standard for this condition. She had a course of steroids initially which boosted her appetite and I managed to wean her off Sheba onto the Prescription food which of course has helped. I have also found that because she is hyperthyroid, her appetite is good compared to the non-hyperthyroid, CRF cats I've had, so if Willow does develop this, maybe - in a roundabout way, it might help (I crush her tabs for this in her food, as pilling her would be impossible).
On the other hand, Metoo is on Fortekor for his CRF -the rescue started this, so my vets continued with the medication in this instance, and he will eat it out of your hand!! BUT, he won't touch any prescription food at all, well, only the dried stuff, which isn't good for his urinary tract problems (but that's another story!)
So, I have two cats with the same condition, but on entirely different treatment. At the end of the day, we do what we can with the individual cat don't we and as my vet reminded me last time, you really can't tell a cat what to do and I guess, that's partly why we love them so much.
Try not to worry too much.