This issue has now been around for about a year. Has anyone figured out how to get voices and death moans back? SingleVoiceVariation helps a little with the frequency of voices, but it by no means fixes it. I still hear only one voice actor
I don't even have SingleVoiceVariation in any of my .ini files. How long has it been since you re-created your .ini files? (By deleting them, then starting the game up). Could be an idea to do that.
If you don't feel like doing that then in your ROGame.ini, search for bUseSingleCharacterVariant and make sure it is set to false.