I was still editing when you followed up. Yes I agree the heavy and lights are 10 kilos wide while all the others are only 5. In the US, the light-heavies seem to be the most crowded class, followed by the heavies, so it would make sense to make those 5 kg wide classes.
but rather than coming up with names, such as light-middle, just do what they do in international events, and go by kilograms