The Forsaken names are all nicknames to ridicule them or out of contempt (except for Lanfear, who chose her name).

Maybe the encyclopedia will contain all literal translations. We know that Moghedien was the name of a tiny, little spider from the AoL, that Cyndane means "Last Chance" and that Be'lal means "the Envious". Probably Graendal means something like "the Decadent" and Semirhage something like "the Sadist".