Maybe their are one or two very slight (unintended?) differences in the 12FG and 14MZ software.
I'm running the following on the 14MZ
Editor: 1.6.0
Encoder: 1.44
I played around with the Rud AFR set to linear 50%, and with a Rud->Rud Prog Mix linear at 100% and was getting a linear +-100%. Using J2 (my throttle stick) as my fine tune input to vary the mix rate to alter the total rudder output.
By setting a non-linear AFR and/or non-linear Prog Mix, I could get a non-linear rudder to rudder-stick response but can't achieve a non-linear Rudder total AFR to Throttle position behaviour.
Looks like someone in Futaba's software dept. messed up bad and needs to be beaten with a pillowcase full of old 14MZ batteries