What is the right course of action now?

Your choice to allow any cross traffic the right of way is correct. According to German traffic rules, when traffic lights are flashing yellow, they do not regulate the flow; instead, drivers must obey the posted traffic signs. In this case, the "Give Way" (Vorfahrt gewähren) sign requires you to yield to any vehicles coming from other directions before proceeding. This means you must slow down, prepare to stop if necessary, and only continue once it is safe and your right of way. Waiting for the next green light or driving quickly through the junction when yellow is displayed is incorrect here because the flashing yellow light signals that the traffic signs, not the lights, determine priority. Understanding this rule helps ensure safe and lawful driving through intersections when traffic light systems are not fully operational.