I honestly like all of Rosalina's voices she has had throughout her various appearances. And thus, I am happy for you to draw inspiration from any of them! As Rosalina has previously had a reverb/echo effect, adding a little audio editing is A-Ok!

Rosalina is depicted as a generally wise, kind, and mature character. She has an intimate knowledge of the universe and cares deeply for the Lumas and her friends, to the point of assuming the role of total caregiver and mother figure for the former. Her outward strength and inner sorrow, as shown in her storybook, are likely due to the loss of her own mother. Rosalina is a calm and reserved character, and often takes pauses when she explains how the universe works. It has also been shown that Rosalina's voice is rather monotone, even when she is excited.