I'd have to start making cold guesses, but off the top of my head I would throw out strange effects on space due to UA as a primary safe space for crafting an explanation. Perhaps the dome, accelerating through space, has reached the point where it is warping space in such a way that it would cause ripples which distort light enough to show a lensing effect? But then, I can think of other issues that UA introduces much more local than our view of the stars that would need to be worked out.
"God made it that way to test our faith" could also be a reason. You know, like fossils. Hard to refute, if also hard to accept.
In a non-Euclidean model, all bets are off because space would be all bendy anyway. Which, come to think of it, reminds me that bendy light has all sorts of strange properties and could be a prime candidate for an explanation.
I'm just spitballing though. Frankly, I think Relativity has shown a lot of predictive power over the years and a FE model would be hard pressed to explain all of the successes that Relativity has been able to shed light on, and then go further and demonstrate further predictive power in its own right.