It seems that I am not the only person interested in Severian of Gabala. I have come across a series of publications by Remco F. Regtuit, who is assistant professor of Greek at the Rijksuniversiteit Groningen.
So far I have seen none of his works, but articles on “The Charm of Severian of Gabala” — something I have noted myself — suggest good things! Unfortunately none of this material seems to be accessible online.
One interesting publication I learned of is Henning J. Lehmann, Per piscatores: studies in the Armenian version of a collection of homilies by Eusebius of Emesa and Severian of Gabala, 1975. This is research on a collection, published between 1956-9 in Handes Amsorya by Nerses Akinian, based on Ms. New Julfa 110. It sounds very like the collection published a century earlier by Aucher, which perhaps exists in several manuscripts.
Another is an edition and translation of an unpublished homily, ed. by Aubineau, Un traité inédit de christologie de Sévérien de Gabala : In centurionem et contra Manichaeos et Apollinaristas. Cahiers d’Orientalisme V. Geneve, 1983.
But once again, how do we access any of this?