I assume that the chances of you getting frozen are decent. I mean no matter how many proxies you are using, the reality is 20 accounts at once can't have good chances, especially since you are score sending which can typically be problematic even just to get certain avatars, let alone be the sole method of production of money for the account...
Also there is no way you are going to get away with autobuying on 20 accounts at once and get away with it... I mean I just assume that's highly risky