AFAIK (and according to
Tolkien Gateway) Eärnur wasn't canonically turned into a Nazgûl. He just went off to fight the Witch-king and never returned. He's presented as what you describe only in LOTRO, AFAIK.
And didn't we have Aragorn as a leader for Arnor in the slot Eärnur is on the list you posted? I don't remember him coming up before. I don't think he fits as an Arnorian leader either (as important as he may have been to Arnor) since he was king of Gondor far after the kingdoms officially split. It would be like having the president of Lithuania as a leader for Poland.
Personally, I prefer Helm as as the Rohirrim Leader and Éomer as a captain or hero, since Helm actually was king when what he's most known for happened, and Éomer was most important when he was just Third Marshall of the Mark. He did become king, but after everything was already over.
I wasn't paying attention before, but didn't we agree to merge Isengard and the Dunlendings, or did I just totally miss something?
I think the Teleri are OK with dropping Celeborn and just having two leaders, since both Olwë and Círdan stand out as being seafaring leaders (and seafaring is what we're going for with the Teleri), while Celeborn really doesn't.
Finally, I think the Fëanorians should only have Fëanor as their leader. I think that they as a civ should have something special with the Sons of Fëanor, maybe (like I said before) something like the Grigori Adventurer.
Rest of the list is wonderful. ^_^
As a side note, if we're calling the Elves Quendi, then we can't forget to call the Dwarves Khazâd.