The word was never "Arcadian." In English, it's Accaddian or Akkadian, and refers to the civilization in Mesopotamia which replaced the Sumerians. In French, that's Accadie and Accadien (or Accadienne). The fault lies in you.
Obviously, i was wrong about how them French spell Accadia . . . they only use one "c." That's cuz they just have to be different. They even infected our park service--Acadia National Park. That's where The Girl fell off the side of Maine. Luckily, she did not fall into the ocean.