It radiates celestial coolness. I like it. She could always go by
Nina, so I think it's usable.
Out of your combos, I like
Saturnina Belen and
Saturnina Claire the best. I like it best with one syllable middle names (or two tops). A middle name with more than two syllables seems to make the combo sound like a mouthful.
Others:
Saturnina FleurSaturnina PearlSaturnina ColetteSaturnina CosetteSaturnina LaureSaturnina FernSaturnina Fay /
FayeSaturnina May /
MaeSaturnina Maeve