A system comprising a host machine and a status projector. The host machine is in electrical communication with a set of sensors and a welding controller which generates control signals for controlling the welding horn. The host machine is configured to perform a process, thereby to process the sensory and control signals as well as a quality state of a weld seam using welding horn formed predict what comprises that any suspect welds are identified. After that, the host machine activates the status projector to illuminate the suspect welds. This can be done directly on the welds or on a surface of the workpiece in the vicinity of the welds using a laser projector. The system and method may be used in a particular embodiment, the ultrasonic welding of battery tabs of a multi-cell battery block. The welding horn and welding controllers can also be part of the system.