So the HVAC company came today to address 2 problems. First was the missing heat vent and second was the howling noise coming from the air return vent.
My suspicions were correct for the first problem. The HVAC company did cut a hole in the duct for the vent but the drywallers dry walled over it. Problem corrected. HVAC company cut out the hold and installed the ventilation grate.
Second problem was corrected by cutting another hole for another air return vent. Should've been two the supervisor said. I only had one which was not sufficient enough for the size of the furnace.
Overall quite satisfied.