@User :

static double
agauss(double nominal_val, double abs_variation, double sigma)
{
    double stdvar;
    stdvar = abs_variation / sigma;
    return (nominal_val + stdvar * gauss1());
}


static double
gauss(double nominal_val, double rel_variation, double sigma)
{
    double stdvar;
    stdvar = nominal_val * rel_variation / sigma;
    return (nominal_val + stdvar * gauss1());
}

This is code from

ngspice-36/src/frontend/numparam/xpressn.c

. So it looks like percentage values from spectre need to be divided by 100.