Coming right out of left-field there is some potential that Domninos was a fiction of Malalas. Sulochana R. Asirvatham her Jacoby entry on Pausanias of Antioch comments: "Of the seventy-five sources whom Malalas cites, those whom we possess are misrepresented frequently enough to suggest that Malalas was paraphrasing at best. Even worse is the apparent presence of a number of fictional authors in his text: for example, five universal histories that Malalas quotes repeatedly but which are not attested elsewhere, in addition to Eustathius whom he mentions infrequently. One of the unattested universal historians deemed fictional by Treadgold is ‘Domninus’, whom H. Bourier saw as one of Malalas’s main authors (believing in fact much of fragments 10 and 11 belonged to Domninus and not Pausanias (H. Bourier, Uber die Quellen der ersten vierzehn Bücher des Johannes Malalas (Augsburg 1899-1900), 9-12)".
The source for Treadgold is W. Treadgold, The Early Byzantine Historians (New York, NY 2007), 235-56.