I think in other games, like SOTW or even Queen Of Thieves, I mentioned the fact that yes, dark elves are more or less accepted in Grandtree. But Icesilia is far away from Grandtree, and after Loren 2 events, everything is a bit of a mess (human empire collapses and is split into region/city-states etc).
Besides it's not like elves are robots: even Myrth welcomes dark elves to Grandtree, and even if many agree with her, there are still a lot of "Mr. Evil Elf" who think Myrth is stupid and they would like instead to kill dark elves babies

They're living beings, each one with his own mind / opinion about every matter, including what to do with dark elves! Even in Amber, she will be treated differently because she is dark elf both by elves and humans. There will be elves that hate her, other that love her (ahem, Lair is one) and other humans that dislike her as well, etc.