I recently installed new nut holders that I designed. These may or may not fit in your machine. But the idea is to eliminate the possibility of the nut turning even a small fraction of a turn within its well - yet still allow the possibility for the nut to "back out" of its well if the printhead lands on the bed (or some obstruction).
Print two of these at 100% infill, and very fine layer height (0.15 or 0.1mm). Then use fine sandpaper to smooth the curve even more. Use sandpaper or a file to remove all burrs and flash; get the dimension from the curved side to the flat wall as close to design as you can: 10.16mm. Lubricate. I glued these into the well with a small amount of silicone glue (using a nut during curing to hold good pressure on the part, so the layer of glue did not throw my dimensions off).
It will take a little force to get the nut to enter the space between the new part and the opposite wood wall because we want to have a spring action that perfectly immobilizes the nut from rotating. I printed mine with Taulman T-Glase because that's what I had in my extruder - but nylon would be a little better because it's more flexible. It will probably work with whatever plastic you use.
Z-nut Insert.jpg
The piece will put the nut into a "vise" between the plastic insert and the outside wood wall, so the nut can't rotate.