The new perspective works much better, but the leg closest to the camera still doesn't seem to match that perspective. I think that the effect you are looking for is not the "fish-eye", but rather an extremely small focal length of the camera. Try tweaking something related to focal length in the camera of your 3Ds Max mock-up, maybe you'll find what you'll looking for.
But in any case, even if you found the settings under which the legs are projected in the same way, other details could still be ruining the perception of geometry and space. For instance, the front left hoof appears as if we are looking at it down from above. The way the shadow from her front right hoof lines up somehow seems to reinforce that way of perception of space, and makes it like she has a humongous oversized front left leg :/
Perhaps even more importantly, the scale of detail on the carpet stays exactly the same as we move from her front right hoof to the left hoof, while the hooves themselves change in size dramatically. This is probably what flattens the image the most.
Also the star-shaped gem seems to be slipping off the edge of the carpet. I understand that this effect would occur to some degree in an actual lens due to aberration or something along those lines that makes the the "fish-eye" perspective possible. But you might want to
take an actual photograph of objects arranged in the same positions and see for yourself how that actually works in the real world.
I tried painting over your image to suggest how some of the stuff I mentioned might be corrected. Keep in mind that I'm still very much an amateur and may be completely wrong.
Things to note in my overpaint:
1. The base of the front hoof if flattened, and stands firmly on the ground. The same goes for the 2 closest gems.
2. The rear right leg is moved further to the back. It can't be closer to the viewer than the
front right leg, right?
3. The left shoulder is slightly bigger. This makes the change of size on the front left leg to be more gradual. But it still looks like too much to me :/
4. The front leg has higher contrast (darker shadows and brighter highlights), while the other legs are dimmed. This little trick makes the viewer perceive the front leg as being closer. I also added some reflected red light from the carpet to the front right leg.
5. The scale of detail on the carpet is much bigger in the foreground. What I roughly painted there is sort of out of focus, merely a suggestion, but you might actually have to paint some individual threads of the carpet. The size of the front hoof and its being in focus kind of dictates that :/ Good luck with that!
6. I'm not sure about this, but since the sun is essentially illuminating her hair from behind, the edges of her mane have a golden glow, while the rest of her hair is mostly in shadow. In fact, this should apply to the rest her body as well (coat is hairy too).
7. There's a clear highlight on the carpet from the sun that is shining through the hole in the back wall. I'm quite sure
this lighting is still incorrect, and you should
carefully consider where your light sources are and how they illuminate the room and
especially the main character.
Finally, you might want to work on the wings and feathers. Here's a good example:
By the way, I do like your colors very much.
And thanks, I'm glad you like my gallery!