The formula to balance ride rate does not involve the min or max. It is frontspring/front%*rear%=rear spring. Your calculator is giving higher ride ride rates for >50% weight and lower rear ride rates for <50%.
I don’t use matched rates for drifting. I use .2 hz or greater difference, stiffer in the front.
Ride frequency is the rate at which an undamped, sprung mass will oscillate when disturbed. Determining it in Forza requires a simple calculation, using wheel rate and sprung mass. I’ve changed the formulas in the tables from simplified versions, to Hz = 1/(2π)(N-m/Kg)^2, with 10-decimal conversions from pounds to kg, and N/m to lb/inch and kgf/mm.
I think you misunderstand the proper use of the sheet. There isn’t “single” correct output. Pick your ride frequencies, try different rates. Pick your overall roll bar stiffness, then tweak the final balance as you wish. Pick matched damper values, shifting up and down as you need, for rebound and bump, and polish it off with test driving and fine tuning.
Horizon 4 rally suspensions have more travel and lower minimum spring rates. Look again.
For the ratio matched damper balancer, I took my Newton/kilogram/newton-meter-second damping ratio calculator (for another game), and wrote a formula to calculate the matched rear damping ratio value from the front damper value, weight distribution, and spring balance. Vehicle weight and spring rate are not necessary because Forza dampers are unitless, and there is an arbitrary range of weight-matched values to choose from. If you expand the hidden columns on the right edge of the sheet, you’ll see the un-rounded ARB values, and un-rounded ratio-matched damper outputs.
The front outputs of the ratio-matched section has the same weight correction factor as the simple damper section (critical damping increases by the square of the weight increase). The rear outputs read the weight distribution, and spring inputs. If the spring rate balance matches the weight distribution, the outputs of both damper sections will be the same. If the rear ride rate is lower, the rear dampers of the second section will be lower, and vice versa. I’ve compressed the damper output range, applied the scaling factor to both sections, and added a toggle in the rear ratio-matched/precise outputs that falls back to the simple outputs if the rear spring input field is empty. If you’re using balanced ride frequencies you don’t need that section anyway