Put simply, what are we seeing when the sun sets? In RET this is easy. In FET it seems that it should always be possible to draw a straight line from where you are to the sun, since the sun orbits above the plane of the earth. Light from the sun may not always be shining on you, so the sun may go dark from your perspective, but it should do so while in the sky. I don't see why it would go below the horizon, and then rise up from the horizon on the other side.
The same applies to the moon and, well, every star in the sky. If you watch the night sky, every star moves in a circular path around a single central point. The whole sky rotates in unison around the celestial north or south pole. Which makes sense if the earth is rotating, because then everything just appears to move. But in FET, it seems that we have to conclude that the entire universe rotates around us, which is quite a thing to imagine (what causes this rotation?) but moreover the rotation isn't parallel to the plane of the earth, it goes around it, i.e. above and below it. That is what we see.