Manifest probably listed her ethnicity based on her *country* of origin (residence) - ship manifests are in many cases wrong when it comes to that.
Her ethnicity must be established through other, relevant original sources - like her birth record.
You need to either corroborate the exact location and surname in (then) Austrian coastal town of Volosko, or the connection/migration to Bosnia.
Serbian Genealogy Society SGS "Rodoslovlje"
http://www.rodoslovlje.com/en