Bouncy Ride - Are springs too stiff?

Car is a R32 GTR. When you go over a bump, not a sharp jolt but more a smooth bump the car is bouncing afterwards. Very noticeable if you push it in a corner and there's a bump.

Winding up the damper (+) reduces it a bit but the ride gets pretty harsh.

My initial thoughts are the springs are too stiff?

Previously I had old Tein Type HA in there, and although they were noisy and probably at end of life they performed much better. The car was very low then (330mm front and back) and I believe the springs in the Tein's were 7kg front and 6kg rear.

Current Coilovers are a kSport kit for the r32 GTR.

Fronts are: 66-180-10kg

Rears are 66-200-7kg

Ride height currently set at 355mm front and 350mm rear (factory ride height is 370mm front and 360mm rear). I plan to lower the rear another 5mm and/or all round a little more but I don't want to go back to 330mm which was too painful for driveways etc.

I have checked installation procedure with the installer and KSport, all seems to be done correctly and Ksport say they are the springs they usually use in the r32 GTR for sport use.

Car usage is for spirited Sunday mountain drives and very occasional track days, still wanting a little comfort for coffee runs.

I know there are a lot of variables but is trying softer springs the next logical step given I've already tried the different damper settings which are the only adjustment on these coilovers?

I've done the suspension course but it was a little while ago now.

Thanks in advance.