Very intriguing! I had imagined Dorwinion was Mannish, but I guess if it was Avarin that really would be a more logical explanation for the CoH reference, and perhaps of the potency of their wines as well.
This is a later incarnation of some of the religious beliefs that you sketched out at Cuivienen? And the Queens are Priestesses--is being a Queen a job for life in Dorwinion? Also, are you saying that Dorwinion was allied with the Wainriders who fought against Gondor (although they seem opposed to Mordor?) I am as bewildered by the politics as Tauriel herself...