When you make the clubs longer, the head weight moves further from the fulcrum point on the swing weight scale, so you get the higher reading. It does not mean the club is heavier (the head weight doesn’t get heavier), just that the weight is further out from the fulcrum point. That being said, longer clubs can feel heavier, swing heavier, to some players because they are longer. The only way to counter the effect the length has on the swing weight is to counterbalance, or remove weight from the head. I don’t to necessarily recommend removing weight from the head, so that leaves counterbalancing. I wouldn’t get so focused on the swing weight number that you forget how the club feels. If you counterbalance too much the club could then feel too light. May take a little testing to figure out, at your length with that shaft, if D4, or D6, or D8 is the number that makes the club feel right for you at your fitted club length.