My original point about the tsar pattern was that if it is so different than the "usual" stuff implied by king, queen, etc, than having words that so closely resemble the pattern used for something very closely associated with that very paradigm is going to cause problems.
And exoticism for exoticism's sake only reminds the reader that they are reading...it kicks them out of the story. Although it's not quite as bad as metafiction for that. In any case, if her test-readers say they have problems with it, I think she should listen to them- or at least give something else a try. It's the hardest bit about writing *anything*- fiction, non-fiction, news articles, essays, research papers, speeches, etc etc...
Murder your darlings as they say