There was no Eastern Roman Empire after the thrones were formally united in 476. If you want to call Byzantines Roman, then it's just Roman Empire.No, they should be (Eastern) Roman Empire. But that's not really the big problem...
Dynastic names like in CK2 would be the best for states like Ming, the Mamlucks or the Ottomans.
Though I agree with dynastic titles for some non-European realms.