These plots show that each LL has ~0 non-linearity at lest at some HV except 14 nA LL. The non-linearity value for 1000 V HV at 14 nA LL seems to be the smallest one but it's X2 value was too big so can be considered as statistical outlier. There are many HV/PreAmp settings having close to zero non-linearity for 0.3, 0.5, 0.7, and 6 nA LLs.
