You know what you do to get back at them. Cross breed a war horse with a trison! After you get a unicorn, bicorn, And a tricorn, you need to change your surname to horse-lord and commission every map maker on your server to label your ranch, Unicorn Ranch.
Alternately, reach out to the devs and explain that you understand that there is no unicorns in Elyria, but your family name comes from a long told myth in your family history of a fantastic beast that was never confirmed to exist. Do understand though that if they don't even want references to creatures like unicorns it is because they are trying to set up the world in a consistent vision, and although they are trying to allow us freedoms there has to be congruity.