This is not typical when treating abdomen or flanks but is theoretical possibility when treating off label areas such as thighs or arms that might have impact on a sensory nerve dermatome beyond the treatment area.
Actually it is possible to have numbness outside the treated area and this will usually occur with numbness in the front of the leg or in the groin when the side of the abdomen is treated. This occurs because the sensory nerves running to the front of the leg and the groin acutally run down from the side of the abdomen just under the fatty tissue. If the Coolsculpting procedure happens to cool down this nerve enough, it will disrupt the nerve transmissions and cause numbness. Fortunately, this will be temporary but it can take up to six months to completely resolve.