Correct me if I’m wrong, but chicken is pasteurized at 165F. It can also be fine to eat if left at 155F for at least one minute. There are different reasons for spots on the bones. I wouldn’t associate that to indercooked chicken. Society in general is obsessed with clear running juices and the absence of pink inn poultry … not a sign of undercooked meat. Tell them it’s fine and to trust the chef ;). That said maybe set the temp to 160-175? Any thoughts?
With the connective tissues in legs it’s better to let sit at higher temps to allow them to break down.