assuming that we got that right and didn’t just misunderstand what we are seeing (or assuming that there’s no “side channel” to know how to correct for it)
we also can’t get to a black hole, so for this civilisation it’s safe to assume they have a significantly better understanding of physics than us. we don’t know what we don’t know
The reason that makes it imposible to avoid the dispersion even of a single photon is not technological, it's a theoretical reason. You can't solve it with more advanced technology, you must change the laws of Physics.
It is sure that the current laws of Physics are incomplete, and some may even be wrong, but this effect is so fundamental and the proof is so simple that I doubt it will change.
we also can’t get to a black hole, so for this civilisation it’s safe to assume they have a significantly better understanding of physics than us. we don’t know what we don’t know