Chinese chicken balls - should the chicken be precooked?
I think this is a heavily westernized version of, em, Chinese &quot;chicken balls&quot; (鸡球 ji qiu). The more authentic version comes without the thick batter; instead it's just slightly coated with potato starch. Also, they're not served directly as a dish, but instead used as an intermediate ingredient; you can make, for example, kung pao chicken balls, sweet and sour chicken balls, or spicy chicken balls. (That should explain the lack of batter.)
But in any case, no, you should definitely not precook the chicken. With or without the batter, the deep frying is enough to cook the chicken. If your chicken is precooked, then it is going to become overcooked.