I would pronounce it [name_u]Mel[/name_u]-ee-ah-nah but that really is a guess.
I would pronounce it mel-LEEN-ah
At first glance I also read it as [name_u]Mel[/name_u]-EE-na, which, for me, has the unfortunate homophonic association of melaena/melena which is black, tarry stool associated with upper gastrointestinal bleeding. I think the [name_f]Melina[/name_f] speeling makes it less related, but still sounds the same.
I understand that you prefer the [name_f]Meleana[/name_f] spelling, but I think responses to this thread show that she would be in for a lifetime of spelling/pronunciation confusion, and as you’ve also said you don’t want this for her, I would respectfully suggest changing to the [name_f]Melina[/name_f] spelling. (As PPs have also pointed out, it would be best to avoid the [name_f]Malena[/name_f]/Malaena spelling, the medical term for bloody stool.)