Usually, frostbite occurs when wet feet don't dry. Walking in the snow won't cause frostbite since the snow gets flung off as they walk about. Frostbite can occur if the chickens get wet feet before they roost and they haven't dried. Then that moisture can cause the tissue to freeze.
A big factor is wind. Wind chill lowers the air temperature. A draft in the run or coop hitting wet wattles or feet will cause the temperature to be below freezing and the tissue then freezes.
When there is improper air flow in a coop at night, the danger comes from the chickens' breath. As they exhale, moisture comes out with the air and can then settle on the combs and freeze. Unless air flow carries this moisture laden air up and away from the chickens, frostbite can occur.
There is really no such thing as an ideal winter waterer. If water spills or drips onto feet or wattles drag in the water, then frostbite can occur. As long as the chickens can stay dry, they will be fine.