Most Japanese wa handled knives are blade heavy, so a balance will be up to 2" forward from the handle. It's not an issue if you are using a knife as intended with a pinch grip or a light grip with an index finger on the spine. A handle in this case is more for a leverage than for a grip.
I balanced a wa gyuto on a couple of occasions, through using 1/4" NS spacer in the front and 1/16 in the back and embedding a small piece o metal in the rear, but it added to the weight of the knife and I didn't see any real advantage from balancing. Most wa hande knives have have at 1/2 -5/8" space between a handle and a heel, so a pinch grip or a forward grip with a finger on a spine is a comfortable way of holding and using a knife.
For full tang western handled knives, the balance at the handle is more important even though many still use a pinch grip.