Zenobia! That one is such a gorgeous name. It's beautiful and underused, and it would go wonderfully with Rosalind.
Now, I am somewhat hesitant about coming with suggestions because you have such a wonderful taste in names, and I could be waaaaay off in my suggestions (because I usually are). However, I am gonna take the chance and mention a few beautiful names:
Aemilia (from Shakespeare's Comedy of Errors)
Gaia (Greek; earth and fertility goddess)
Hespera (Roman; goddess of dusk)
Juno (Roman; Queen of the gods, goddess of matrimony)
Marina (from Shakespeare's Pericles)
Saga (Norse; goddess of runes)
Thaisa (from Shakespeare's Pericles)
Vesta (Roman; goddess of the hearth)
Violenta (from Shakespeare's All's Well that Ends Well)
What will you do if you have a boy? ;)
Rosalind is beautiful and relatively unique without being too weird/bizarre. I suggest going for another name with the same qualities.
Atalanta- a little weird
Ceridwen- a bit harsh and not as beautiful as rosalind
Fiammetta- a bit too foreign but Etta would be nice
Melisande- a little weird
Natasha- really quite nice
Roxana- ok but not great
Zenobia- sounds like a country in africa
Leona (not my real name)
Phina (josephina etc)
Lucia (loo-see-a because it's 'smoother and softer' sounding)
Eliseor maybe one of the names in my signature?
EDIT: (just thought i'd add these)
Corinna or Serena
Noella or Luella maybe
Cecile (i used to love this!)
& i kind of like Odelia! it's not as frilly as Ophelia which i like and i don't think it's too odd or pretencious. actually i think it has the same roots as your name!
Ernessa? some people might discount it just because they have never heard of it! but i think it's better then Odessa which is a place.
Angelica, Amalia, Alicia(uh-liss-ee-a)/Alessia.
PS. i am 'leona' who used to post on here but i think i forgot my password or something and i couldn't access my account! :( so here i am.
I ADORE Rosalba, but you're right - it doesn't go with Rosalind at all. Still - absolutely stunning name that no one else seems to love.
Fiametta seems to be a constant on your list - maybe that should tell you something? It's one of the few names that seems to always creep back in and I have to say that Rosalind and Fiametta would be perfect for sisters.
from the names you mentioned, Serafina and Cordelia are my favorites! I really like Cordelia! I don't understand why you are opposed to using it, though, because right below that you said you like literary references! Cordelia is the good sister/character in King Lear, so it's not a negative reference. Natasha and Melisande are also okay from your list, but I don't think any of them (except Serafina and Cordelia) are adorably old fashioned and unique enough to go with Rosalind.
Ella (I think this is adorable with Rosalind!)