What is the planet farthest from Coruscant in the Star Wars Galaxy? I understand that this information might not be available. If it isn't, please tell me.
Assuming the opening scrawl is correct, I'd say that the single farthest Earth-like planet that we know of (from Coruscant) would be Earth.
If you're talking "in-universe" but aside from The Galaxy itself(but say ones that have actually had civilizations come into contact with The Galaxy still) there are a few options. Yuuzhan-Tar, the original, as well as some of the planets from the companion Galaxies that have had invading hosts enter The Galaxy at prior times are all possible contenders for "farthest known planet from coruscant" in an absolute sense.