But RL's point is that actually changing them to a cat's eyes is not necessary for the spell effect - in fact, it has nothing to do (except cosmetics) with the desired effect, which is merely to gain a minor ability, in that case, to see in the dark. Nothing about "seeing in the dark" has to be tied to an animal - it's merely creative and colorful to do so - hence, cosmetic.
~IF~ the Guidelines were to read "give an animal ability (with requisite)", that would be inarguably different. But they don't, so it's open to interpretation.
(Note that a lot of this is legacy effect - The Guidelines don't say you gain the organ of an animal, only an un-defined minor ability- they don't say how that must manifest. As mentioned elsewhere, the spell could be called "eyes of the night walker" and we ignore the whole "cat" thing entirely.)
However in the case of the spell in this topc, to give a statue the shape of an animal is not, imo, purely cosmetic - it is arbitrary and open to the whim of the mage, but there is a concrete element to the final form - it's not merely a bit of glitter attached to the spell to make it shiny and cool.
And there is, to me, something essential of the "Form of Animal" about it, as well, a tangible element that is no longer of the realm of Corpus. And that is the dealbreaker (for me.)
But it's admittedly a close call, and one way or the other has solid justification. The key, for those players and SG's faced with such a call, is to make your decision based on reasoning, and apply those reasons across the board, so that "magic" in your Saga has a solid feel to it, and is not just a string of arbitrary and unconnected rulings listed together under the heading "houserules".