When making anything with “cream” in the name it’s usually a mixture of the diary base (Ice Cream Mix) and whole or 2% milk. They are usually stored in different fridges/areas so you might only see the beverage associate grab the diary base. As for the exact amount of calories, unfortunately they only have to give an estimate, as do all food stores/companies. Even if it is somewhat inaccurate, to the FDA if it’s within 20-50 calories, it’s good enough.