I have a feeling it's a "I've missed something really small problem"
My unicorn has a zoopedia, but it won't link from the book icon directly - you have to find it manually (it's also European Unicorn, not Unicorn, European, though it's in the U section.)
Also the location in the zoopedia stays constant, but on the selection screen it stays as the last animal to be selected. I've used the alternate lang tutorial for ES (instead of that section in APE2) so the unicorn could come from anywhere from the african desert to the arctic =P
I think it's the AI or the lang files, but I can't find what bit in particular is the problem here?
Edit: I've just figured the "Unicorn, European" problem out, nevermind for that part =P
Edit 2: the AI file has:
Is that correct?