"She had unusually good skills piloting the Falcon, knew how to fix the Falcon, understood Wookie language"
likely because she has previously spent time with them as a child... we see in Rey's flashback the junk dealer (who is in possession of the Falcon) taking her hand... we see him on the com as soon as Rey takes the ship...
perhaps it isn't Leia's place to say something... if anything, for Rey's own protection...
the final scene between Luke and Rey... my guess is that look on his face isn't simply because of his old lightsaber...