the term "royalty" has been used to describe deposed rulers even where the country no longer really exists or atleast, isn't a monarchy anymore. while it implies direct relations to a king, once that tree wraps around itself a couple times and you start talking succession, it tends to be forgotton. in other words, while webster might disagree, we could be dealing with a third cousin, twice removed, of some nation wiped out by the cataclysm, hence still royalty
further, while i haven't played the tutorial, from what i hear it seems to suggest a non-intuitive use of the term "sovereign" is being used to describe the player character and the "leaders" of the nations, this is reinforced by the fact that the description for praiden and other nations, describes them as being found by some ruler, not your character, after the cataclysm, yet the player character is very clearly rebuilding after the cataclysm. praiden is ruled by queen procipenee(or something like that). implying the soveriegn may not actually be royalty. which is not unheard of, being that in history there have been numerous occasions were a king or emperor has been nothing more than a figure head. the shoguns, for example
then again, maybe we should just take up a collection and buy the developers a dictionary for christmas.