I'm not quite sure I follow the excel you show as you seem to have a 4th order polynomial and an exponential plot, but no 2nd order polynomial (quadratic) which is what NLE actually uses.
However, one thing that is clear is that you need ~1.56x more extrusion at your max speed than min speed you tested (100/64). First question: is that really true?
Second, what NLE command do you actually have, and have you specified an L parameter? NLE is limited to a maximum factor of 1+L, and L defaults to 0.2. If you haven't specified one, you won't be getting anywhere near the amount of NLE you need at higher speeds (1.2 is a lot less than 1.56). My guess is this is why you are having issues with your e-steps as anything above ~7mm/s would not get enough NLE based on your excel.
Link to the docs for ref, but I guess you've already been there!
https://docs.duet3d.com/User_manual/Reference/Gcodes#m592-configure-nonlinear-extrusion