I would like to point out a key word:
possibly an offshoot of the Deldrimor dwarves. This means it is just similar to deldrimor design. Doesn't mean they are. However, as I brought up
in this thread which is a research of the Depths of Tyria, there are far more similarities between the structures of Tyria and Cantha (and even in Elona), so the Aurios Mines may be part of those similarities.
I believe there were many races before humanity (as the Depths of Tyria predate humanity according to the EN manual) who created structures in Tyria, Elona, and Cantha - with Tyria being a bit of a mixing pot.
As for the the deldrimor dwarves' stone being green. Huh? I never seen them green, the ones in EN appear to me as a bluish grey color, not green. Perhaps it is the lighting?
Oh, and it is impossible to have setteled in the Aurios Mines seeing how that it smack dab in the Jade Sea - unless they were breathing underwater or ship dwellers, they were not there. They could of been around there, however. But I find the most likely situation, given our knowledge, is that there was some ancient trade with the Deldrimor Dwarves and Cantha, and shortly before the Jade Wind a ship or two lost some containers of dwarven relics.