You can see here the nut of the same guitar with the same strings like it is on Pepi II made in a different and more sophisticated way.

To compensate a minimum is one way and to overcompensate is the other way to approach to the optimum.

I am these days trying out an overcompensation of 3 mm for all the strings knowing, that this can be the solution only for one or two strings.

It seems to be too much for the thin strings. They really beginn to sound flat, while the thick ones still sound very harmonic.