Hi
Can't comment directly on T4 balance, but I occasionally use the 4 scale method to check for tweak on my T2 '12. Some tips:
1. Make sure the surface you are using is perfectly level (use a spirit level to check)
2. Use setup wheels to make sure weights and sizes of the wheels are equal (the plastic rims you show in your pic are probably OK)
3. Check the anti roll bars are not twisted
4. Check that the chassis is not tweaked (loosen the topdeck with the chassis flat on a setup board and re-tighten)
5. Set the ride height equal front and rear
After all that ........recheck. If the corner weights are still out, then adjust the spring seat screws
It is NOT unusual to find quite big differences, and these are usually on a diagonal. (You will be surprised how little screwing in/out it takes to even things out - spring rates are around 250g per mm so 100g = 0.4mm adjustment !). If you screw down 1/2 turn on the left front (for example), adjust the right front up by the same amount so that the overall ride height does not change. It's usually not worth trying to balance to better than 5g difference. On the T3 '12, all 4 corners end up pretty equal - but depends a lot on battery & motor weights.
HTH