yeah one named alchemist on the entire map is not enough obviously.
You should have a quick look here:
Darmok needs approximately 100 kills to spawn. Good luck mate.
But i can confirm he’s not broken, since i was Lucky enough to catch him 2 weeks ago, so you may find him eventually, but it’s just crazy how low are the spawn rates for some named right now.
As for archpriests there are some places where you can get them in a fair amount of time compared to 1 single placeholder like darmok.
however i’m still not 100% sure but i strongly Believe there is at least one other spot to catch him.