I gave it a whirl. Sure enough, the Add menu in the header and Shift+A menu are empty for Armory. I have filed a bug to the tracker.
As Reiner mentioned, we rebuilt the nodes “add” function to be ergonomic and more organized, and iconized. For some addons like Animation Nodes, the workaround to populate the add menu has had no issues. The shift+A add menu for Sverchok also works. Even addons that build new tabs work (Matlib, Node Wrangler, etc) But Armory does not. Might be worth retrying it out after BFA get’s build on Blender 2.8’s master source code released probably around September 2018.
I have some errors from Sverchok, which also have custom nodes.
:dance: