According to the database the
Ros- in
Rosamund also comes from
hros. But I would guess that with both
Rosalind and
Rosamund, they were influenced by "rosey" meanings, spellings, and probably pronunciations.
Rosalinda, for instance, is pronounced RO-sa-linda, and it's not incorrect - especially because it also means "pretty rose" in Spanish. This database even has
Rosalind pronounced with a long O from that influence.
Basically, I was just trying to say that past etymology of an old language doesn't necessarily dictate current pronunciation in modern languages.
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"We are all horrible and wonderful and figuring it out." - Harris Wittels