And in the EA model, why does the sun appear to dip below the horizon?
Because the Earth eventually obstructs your view of the Sun.
But if the sun's light curves upward, the earth doesn't eventually obstruct your view of the sun. You'll see it below the earth's obstruction, like a mirage as the rays which are bent tangent to the surface continue on and bend upwards.
Unless, at those angles where that would happen is where the spotlight effect takes over.
Edit:
4 hot air balloons: A, B, C, and D
Which one(s) would see the sun in this graphic and, if seeing it, where would they perceive it to be?
It may help a bit if you don't look on the lines on the Electromagnetic Accelerator diagram as rays leaving the sun but from the other direction as the direction an observer would perceive the sun.
So, for your balloons, the directions have not yet been defined, but would, presumably, match "reality".
From directly below the sun it appears directly overhead but from other locations the sun is not seen as being in its geometric location but lower.
Every point on the sun can still radiate light in all directions.
At least one flat earth video uses a bi-concave lens to achieve a somewhat similar effect, this one, I think:
Flat Earth Dr Zack's Angles of Deception, Fudmottin
The big problems with Fudmottin's lens are that it is effective only for a limited range and only if the sun does not move.
So little seems defined for the Electromagnetic Accelerator that there is no way to know if would be effective were the sun to move.
It's fair to say that, at this stage, it's only a hypothesis and not fully developed.