Nice! Good job! Though maybe "Antediluvian Arena" would be a better name since it fits STK's naming a bit better? (e.g. Antediluvian Abyss, Cornfield Crossing, Candela City, Shifting Sands, etc.)
Contributor to/fan of STK (Upstreamed Cartoon theme, numerous random big fixes/tweaks)
Around the Lighthouse, Black Forest, Green Valley, STK Enterprise, The Old Mine, Nessie's Pond, Volcano Island, Cocoa Temple, Oliver's Math Class, Fort Magma, Snow Peak, Northern Resort...
I really don't think that doubling the initials (which is also often lost in translations anyway) is required.
I have played arenas a very few times, so, I can't give you the proper feedback upon the fun of a battle in Abyss Arena, but I can tell you my impressions about the construction of this arena. I think you did a good job using an existing track and improving it with objects and nicer details.
Congrats for your work.
"Making cool harmless games makes the world a better place".