Based on your description of the artwork "Regatta on the Grand Canal in Honor of Frederick IV, King of Denmark" by Luca Carlevarijs, the element that is least likely to be present is symmetrical balance. This type of balance typically refers to a composition where elements are arranged equally on either side of a central axis. In scenes depicting regattas with boats and many people, the composition is often dynamic and asymmetrical, reflecting the natural and lively activity rather than a balanced arrangement.
Thus, the answer is:
symmetrical balance