I'm one of the creators of the cat/hyena things in the Warrior Cats Roleplay (with much appreciated help from my companions), and I'm truly flattered that those were mentioned! c8
And on the subject of strange mixed-up species, my answer is, why not?
I say, if someone wants to make a character that's a part cat and part dog, or part horse and part donkey, or even part zebra and part lion (anything, basically!) that it's completely up to them, and they should do it if it makes them feel happy about it.