I noticed an ad for Renalzin recently and have just looked at the website, the ad was about using it from age 7 for prevention, but the site seems more focussed on CKD itself. Anyway, it has a
recipes section, including such feline culinary delights as fish cookies

Although it makes me smile, I know I'd have tried anything to get a renal cat I had to eat, so it might be worth bookmarking at least for any moments of desperation. Or just for a treat
My renal puss HATED the renal diets with a passion & there was no way she was getting adequate nutrition from them. The vet said to feed her anything, it was more important that she ate & maybe try the renal stuff again when she was feeling better (but she continued to hate it). Meal times were a bit of a nightmare, it seemed every time I managed to find something she kin of liked, she stopped liking it & it was commonplace to go through 5, 6 or more different types & flavours in the hope she'd eat anything. Thankfully she liked
Applaws which comes in a great variety of flavours & although it sometimes went out of favour for a while, it was THE most reliable food for her. It is quite 'healthy' for renal cats too & is overall a great food and definitely something to consider to boost any ailing cats appetite. Could probably use it all the time for 'normal' mogs, but
it is quite expensive! Most cat food brands have an age 7+ range, but noticed Royal Canin now have one for
12+ (dry & in pouches) which has lower phosphorous in it & something to stimulate appetite. The kibbles look a bit like treats too, so that might an advantage?!
My mog was also on Fortekor, with monthly jabs of an anabolic steroid & Vitamin B12. She got weighed on her monthly vet visit, but as her condition could fluctuate so much (initially) I got into the habit of weighing her at least weekly at home & the vet showed me how to do a gentle pinch of her neck fold to determine dehydration. They were both useful things to do, especially as she could crash quite quickly sometimes - if the pinch wasn't too bad I'd have a go at trying to encourage her to eat & drink more, but I got to know the threshold to know when not even try & just get her in asap for treatment (fluids). Having (as far as possible) the same vet each time was also useful, especially as her bloods were totally off the scale & often bore no correlation with how she was in herself. The vet was fabulous with her too, they were like a mutual fan club together
Good luck with your mogs, Op. Caring for any poorly puss can be difficult & coping with a chronic illness is a different entity. It's tough to start with and a steep learning curve, but you WILL get there. Just remember to be kind to yourself as well as to those lovely pussycats