Also, try to remember that N&A probably went into production in 1969 or so, the original locations were not available. And, it was a condensed version of the Massie book. That work focused on Alexei's illness, as that is what got Massie interested in the first place; his son has hemophilia,. And, it is impossible to condense a 500+ page book into a 2hr+ film.
Also, the girls in the films are actors, portraying the real persons. The are not meant to BE the original persons, the "look" is enough, if they can do the job, costume, makeup and hair can convey the effect desired.
I agree with Greg King. Romanovsky is sappy and worshipful. Good, but sentimental.
N&A was a different work altogether.