RE: Your thoughts after reading JR 12X manual
I’ve never had a delta wing but this should work. In one of the linear program mixes, mix AILE to AILE. Set both left and right mix to around -70% for POS0. Adjust your linkages to get the throw you need for pitch. Adjust the mix percentage for the roll.
BTW, the MONITOR menu is handy for determining the receiver channel assignments. The upper left is channel 1. Below that is channel 2, etc. The upper right is a continuation of the left column (probably channel 7). The lower right is the last channel. If you have a 12XMV, the number channels shown will depend on the modulation.
Allan
It took 10 hours for this to dawn on me but a simpler way is just go to menu 13 (D/R & EXP) and dial down the aileron rate.