Hi, nice that you got it working. This calibration is intended for the low frequent part so the 128 LUT is (probably) sufficient.
The error you find you need to multiply with the number of pole pairs to end up with the error you make in the electrical angle ‘coordinates’.
The high frequent variations are likely Cogging. The interaction between the coils and the stator. To calibrate that we need a similar procedure but then we need to log the current usage at each encoder increment. That LUT would likely need to have larger resolution
You can actually count the peaks over one revolution and that should roughly equal your pole pairs. However you also have secondary peaks. So it is not always clear, I think