It makes a lot of difference.
This is a major space phenomenon. The Sun reaches out and affects the Earth with more than just light. Does FE cosmology allow for the existence of Solar Winds? Van Allen Belts? A bi-polar magnetic field?
Let me stop you there.
Bi-polar magnetic field? What do you mean? The earth only has a north pole, which all compass needles point to. There is no "south pole" equivalent. Just a north pole.
And what do you know -- the north pole is in the center of the earth (which is a plane covered by a Firmament). Magnetic "south" is any direction outward and away from that center point.
Antarctica is a ring of land around the known world, containing the oceans. Not an island continent on the bottom of a ball.
Van Allen belts are neither here nor there in FE cosmology. There is no outer space, so there is no concern about lethal belts of radiation that must be passed through to "explore outer space".
I know what "solar wind" is. It's a stream of energetic particles (radiation) coming from the sun. Spacecraft could theoretically harness them with a "solar sail" to harvest energy. One of the battered spaceships at the beginning of Star Trek IV (the hunt for whales) said they were going to deploy a solar sail as a last desperate measure. But again, there's no outer space, so...
As for the rest of the sun's effects -- the sun does whatever it's proven (with actual science, verifiable, physical, observable evidence) that the sun does. It has nothing to do with the shape of the earth.
Some of this sounds like "begging the question". You might as well say, "The earth can't be flat under a firmament. If outer space doesn't exist, then where do the aliens come from, hmmmm?"
As Ladislaus said (in so many words), you're brazenly baring your brainwashing and biases for the world to behold.