Honestly I don't think the actors race really matters too much for voice acting. Let the voice directors/casters pick the voices they think best match the characters. If that happens to mean that actors are selected by race, then that is because that's what the voice director/caster wanted. For some stories it works better or makes more sense when the voice actor is selected based on race, and for some stories it doesn't. Let the voice director/caster decide.
This doesn't have to be hard.