This question is asked to criticize the people of Reuben because they did not decide to come fight in the battle. This can be translated as a statement. Alternate translation: "You should have helped us fight, instead of staying at home and listening to the shepherds playing their pipes for their flocks" (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-explicit]])
Here "heart" represents thoughts. The people discussing with each other but being unable to decide what they should do is spoken of as if they were searching their heart. See how you translated this in [Judges 5:15](./15.md). (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-metaphor]])