Let's come up with an amphibian race!

No, it's better not to translate, but to come up with something original. You could create a derivative of the word "Tatalia," or something completely new. For example, the race could be called "Vaer" (Water+Earth) or simply "Children of the Sea and Earth." Or "Children of the Great Turtle" (you just need to come up with a name for it).

Added 1 minute ago

History is what actually happened. And mythology is what they invented themselves, forgetting what it all started with, forgetting about the Cataclysm.