Regarding Severus, Julianism and the Council of Manzikert:
Around the sixth century, Julianism was so fashionable that even the Emperor Justinian took it up before his death. (See Evagrius Scholasticus' Ecclesiastical History, Book 4, Chap. 39) Julianism made inroads into Armenia, but not to the extent that the writings of Julian were ever translated into Armenian. Or if they were, they were never in any way preserved.
The anathemas against Severus were never renewed past the seventh century and so they are, as a practical matter, defunct. Severus' writings were never translated into Armenian, and it seems the Armenians had misconceptions about what he taught:http://www.orthodoxchristianity.net/forum/index.php/topic,16969.0.html
This was straightened out at the Council of Manzikert, in which bishops from both the Armenians and Syrians met and had a meeting of minds on various issues, including Christology.
None of any of this ever resulted in excommunications. There was never a time when the Armenians were not in communion with the Copts and Syriac Orthodox. Did polemics go back and forth between theologians on various issues over the centuries? Of course, but I am sure the same can be said about the Chalcedonians.