I don't see how this is a problem. You used sugar instead of CO2 to prime the kegs. The yeast will ferment it out completely. You will not have extra sweetnbess, only extra carbonation. Let it ferment out, vent off the extra pressure (not sure how but i'm sure it's on here, similar to the process you might use when correcting over carb when doing the shake it force carb method). Then carb to proper pressure with CO2. The only unintended result is a few extra tenths of a point ABV, no extra sweetness.