I lived in Washington state when I was young. The area I was in, referred to carbonated drinks as "Pops". Two counties over, they were called sodas, the county north of me called them soda pops, which is the original term. It somehow became bastardized in other places. You could use any variant in either of the three counties and people knew what you meant.
In a way, that was what I was trying to do, use variants of terms commonly known to differentiate the original races from the evolved ones. When you read the word alpha, for example, you usually are reading about someone who has an aggressive personality who often is the leader. However, a leader only has to be able to get others to follow them. Some of the best leaders I have known were not aggressive.
My point with this is that not just any word will work. Alphas are dominate personalities, so a word like dominus, which is Latin for master, is more likely to convey to a reader, the image of an aggressive leader, than a word that most people have never heard, and are unlikely to be able to guess it's meaning. That is something I want in this story due to the sides being related. In another story, I might make up words.