OK, I'll try that.
I didn't rename the .dds, .bfm, or .nif files, I'll go and try that...
EDIT: OK, after doing that the animal's icon appears, the zoopedia is working better, and I can place the animal without crashing the game. However, now the animal (it's made from the Zebra, by the way) is all white (the mane works looks how it's supposed to, though) and some of the icons in the Zoopedia are replaced by white squares (the animal's icon, the location, and the biome that's under the location)
Also, the conservation status under the animal's 'General Information' changes to the conservation status of the last animal who's 'General Information' I looked at, and the conservation status doesn’t even appear on the selection screen.
I had to remove some of the files because some were originally named 'ZebraCommon', and others just 'Zebra', so I couldn't rename both to my animal's codename because they'd replace eachother, that may explain why my animal is white.