Sforno on Genesis
והחריש יעקב עד בואם, he refrained from starting a quarrel until his sons would have been informed of what happened so that they could be on their guard against their adversaries.
Or HaChaim on Genesis
עד בואם, until they came home. Jacob sent a message to them asking them to return home.
Radak on Genesis
ויעקב שמע כי טמא, Shechem, who had already been mentioned (hence his name does not need to be repeated here and a pronoun will do) and that as a result of what he did, Dinah had been defiled by an uncircumcised person who had been intimate with her.