Is it permissible to call a girl by the name "Malak" (angel) if it is her common name and she refuses to change it despite knowing its impermissibility? And is one sinful for calling her by it? And is it obligatory to call her by another name, even if she dislikes that?

The naming of "Malak" was previously prohibited, but calling a person by this name or reporting about them using it is permissible, because it is merely for identification and not an initiation of naming or an affirmation of it. The scope of reporting is wider than that of originating, so what is not permissible in origination may be permissible in reporting.