Try taking a few loops off of each drop target spring. The spring not only pulls the target down, but it also holds it forward when up. The vibrations of the mech resetting can cause the target to fall back down if the spring has loose tension.

Also, check that there isn't a bunch of slop in the linkage from the coil plunger to the reset bar. If this isn't smooth, it can lead to targets missing the catch lip.

Has anyone heard any talk of CPR making dragonfist playfields? Without their previous preorder list, I have no idea what they're working on now.
If that happens, building one of these will be possible.