If the number of deaths is overcounted (it might be, or it might be undercounted, or it might be overcounted in some places and undercounted in others), and the

If the number of deaths is overcounted (it might be, or it might be undercounted, or it might be overcounted in some places and undercounted in others), and the total number of cases is undercounted (it is; it's just a matter of how far we keep adjusting - we can't gain confidence until we have representative serological surveys), then the fatality rate (and thus almost certainly the mortality rate) is also overestimated. I don't know if that is "discounting the severity", but so far we've watched the CFR go from the announcement at the WHO of 3.4% to paper after paper finding below 1% (sometimes far below). I don't think that these researchers are discounting the severity, I think they're doing the best they can with limited data.