The wellness brands that I have seen do not have a sufficiently low protein to help compensate for protein loss in renal failure. They do tend to use a lot of fish, which is high in protein, though cats do tend to like the taste of them.
Obviously, starvation is not preferable to keeping these levels lower. It is more important she eats than to have the food with lowest protein/phos/sodium contents, but our goal is to find one with the lowest levels, and best for her condition, that she will continue to eat.
If she has elevated phosphorus already, that is when you need to consider that higher priority in selecting foods, and a phosphorus binder supplement would be required by your vet. If not, low protein content is of utmost importance. Reading content % on labels give you minimums and maximums but that is only a guideline, as the foods may have a different quantity than they claim. However, I do know Hi-Tor has been evaluated and deemed suitable for renal failure and used often by vets, while wellness' claim of having a renal failure diet remains just their claim. K/d has the lowest proven protein, phos and sodium levels together for this problem, and in fact aren't a suitable long term diet for cats not in renal failure, which is why it is prescription only. However, as we've been discussing, taste is seriously lacking, and starvation is absolutely not the chosen alternative!
In reading labels and doing the best we can with that info, Hi Tor claims to have a severe minimum in both protein and phosphorus, here's the link:
I am currently looking for more info on wellness and renal approved formulations. Also, have you tried Purina NF kidney formula? Again, picky eaters aren't overly fond of, but a better response is seen than with k/d. (K/d seems to be the hardest to get them liking).