I'm new here and I have no idea if I am posting this correctly, so bear with me.
With regard to St. Severus and the Armenian Church, the answer can be found in Fr. Samuel's book, The Council of Chalcedon Re-Examined. On pages 167-168 of the edition I have, Fr. Samuel points out that the Armenian Church for a while was influenced by Julianism, the heresy which Justinian adopted toward the end of his life. Since St. Severus had condemned Julianism, the Armenian Church initially condemned St. Severus (this I am getting from The Coucil of Chalcedon and the Armenian Church, by Catholicos Karekin Sarkissian, page 215.) However, Fr. Samuel writes that there was a council held in Armenia in 726 which abandoned Julianism and accepted Severus as a saint.
I hope this helps,