Sure, I'm just pointing out that if the premise is that this hypothetical civilization is compute-constrained in some way and so everything beyond our local are

Sure, I'm just pointing out that if the premise is that this hypothetical civilization is compute-constrained in some way and so everything beyond our local area is a facade, they have seemingly wasted resources on making the facade unnecessarily large and detailed. Perhaps the amount is insignificant to them, but it's still pointless waste.