There are two pairs of methods which differ only in register (getDocumentData / GetDocumentData and getDocumentStatus / GetDocumentStatus), that's why the imported module does not compile. Simply change these definitions like this, marking them as overloaded:
function getDocumentStatus(const parameters: getDocumentStatus2): getDocumentStatusResponse2; stdcall; overload;
and the unit will at least compile successfully. I have no idea if it will work as intended - hopefully yes because the parameters differ.
As for the "cannot unwrap" note, this is pretty normal. This means that the importer could not extract individual parameters and imported them instead together as a class, this usually does not cause problems. Just take care with memory management.