I like the idea of Jannah attributing her company’s own awakening to Finn’s, like a ripple effect. Might just be a touch weird she does not react to him identifying himself or that she doesn’t recognize him on sight.
But she does react to him identifying himself. Watch it again. She exclaims: “You!?” But then it’s dropped and never mentioned again even though clearly the concept of FN-2187 is important to her.
That she wouldn’t recognize his face is completely understandable. The FO probably tried to keep his betrayal under wraps, and TFA makes it very clear that troops are supposed to keep their helmets on all the time (“Who gave you permission to remove your helmet?”)