I don't see why plate tectonics can not occur on a flat Earth. Maybe you can enlighten me?
You're the FET expert.
What force, in the FET, can move continents?
You have no rotational centrifuge, no gravitational wobbling and no gravitational unbalance to provoke motion.
My theory is that the Aetheric Winds pushing against the bottom of the Earth cause two major things to happen. First, the Earth becomes compressed as the bottom side is accelerated causing the middle area of the planet to experience very high pressures. Second, the friction of the Aether as it passes along the bottom of the Earth produces heat. As this heat is conducted towards the high pressure middle area of the Earth, the Earth itself begins to liquefy.
And, finally, the heat from the unspent Phlogiston at the center of the Earth seals the deal and causes a vast pool of magma. The upper crust of spent Phlogiston can simply skate around (so to speak) on this pool of magma. Since the crust is fractured, different parts of it can move towards or away from other crusty parts.
So, going by this theory, I do not see any problems with plate tectonics on a flat Earth.