CF definition soft & firm is confusing....for me anyways

They use slow & fast, slow means slow to compress & slow to rebound. This would be the equivalent to increasing compression dampening which make the ride firmer. So if you wish to soften the ride you move the compression setting to faster.
Rebound controls the recoil of the spring, in other words if you compressed a spring without a dampening device the spring would rebound violently. If you have to much rebound control & you hit a bump the spring would "not" be able to return to position to absorb the next bump. So if wish to increase the amount of rebound control you would increase the "slow" setting on the shock.
NMK posted how he went about finding the best ride for his ZF Trail, it is very good. If you search a little I'm sure you will find it.