Actually i have no idea how any of these tools work, i never do any sharpening… i only know about Capture Sharpening because i find it enabled by default in later versions 
No problem 
What if i decrease the Output Level step from 0.05 to 0.01 ?
The Reference Exponent already feels fine-grained enough at 0.01, do you agree?
The algorithm is still exactly the same described in the first post: for each input channel, raise the value to a negative exponent, then apply a multiplier to balance the output picture.
If i understand correctly, i think you’re applying the per-channel gamma correction too late in the pipeline.
You should first raise each channel to its negative exponent (that’s the same as calculating the reciprocal and raising it to a positive exponent), then balance the resulting picture by applying appropriate multipliers, and finally do the subtraction+scaling for adjusting the levels.
In short, do not do any subtraction before entering the exponentiation stage 
Regarding the auto-balance, i do the same as you except i use the median values instead of the mean. That is a bit more robust in case you have some very dark or bright area around the frame, like a film holder, or some direct light visible (sprocket holes?)
After months and months i finally made this test
Here is a sequence of color target shots, in daylight, using Kodak ColorPlus 200 film.
The +0EV was the setting suggested by the camera meter (i’m not sure how reliable it is).
In the second column i calculated the parameters by sampling exponents and balance from the +0EV picture, then i copied those same parameters on all other pictures.
In the third column, instead, i did the sampling individually on each picture, and adjusted the output level so that the median brightness of the pictures is roughly the same. Note how the contrast is completely gone at +3EV.
Right of the third column i wrote the red and blue ratios that i got with the dual-spot feature, by sampling the second and fifth gray patch.
Remember : red ratio and blue ratio are ratios to the reference exponent, so we’re really talking about exponents here
Note how the red ratio drops between +0 and +1EV, then stays almost constant. While the blue ratio drops more significantly between +2 and +3EV.
If this behavior is common to all types of film, i could even compensate for it (that would mean the exponent itself would also be a function of the base, OMG! )
But to do that, i would need an absolute input reference, so i would need to ask the user to sample the film base again… oh well.
Here are the raw files: link