They are indeed Hashmal and Mateus, glad to see the Espers joining in this time around (Minstrel shenanigans would also explain their prescence, we don't know yet). Hoping Minstrel shenanigans ALSO protect us from Haukke Halicarnassus/Omega Halicarnassus headaches in case they need/want to use the Espers/Lucavi's names down the road (like, Altima, Exodus-even-if-we-technically-already-have-Exdeath, the previously "introduced" Belias, and such)