Italian living in Italy, here :)
No, I don't think she will end up as a Rosamaria: if she tells them how to pronounce it, they will pronounce it almost well, because the sounds are not that difficult to make for an Italian speaker.
They will probably find difficult reading or writing it, though. My name is
Michelle and it is never spelled and rarely read properly, but no-one has ever had difficulties saying it.
Side note: in some areas of Southern Italy (where the majority of immigrants to the US came from), it is a tradition to give grandparents' names to grandchildren, regardless if other grandchildren already have it. So, for examples, there will be a grandfather named
Antonio and each one of his children will have a son named
Antonio. The same for grandmothers.
(I hope this is understandable and I apologize for grammar mistakes)