Somehow, Connor's smile wasn't really all that assuring...but the fact that her singing lullabies seems to have a more soothing effect than talking was became her assurance. She remained calm-ish and safe for the entire time Connor was away, and probably could have kept going for as long as he needed. Regardless of how long she could have kept it going though, he did return. Elizabeth kept singing even as he starting to speak hi latin...fading away a bit as he finished his spell and trapped Jacob in that spot. 

She smiled a little at the young hunter, impressed by his latin skills, but not really coming out right to say it. 
'So..you've trapped the ghost.." she said quietly, looking over at agitated Jacob, "What do you plan now?"