The region of chargeability doesn't determine where you interview - many people live far from where they were born. But: yes, she should have put Argentina and got a SA number. Ordinarily this would be a disqualifying error. However, assuming you were born in Australia and also meet the DV requirements then she can cross-charge to you /Australia. Technically if she was to do this it should have been indicated on the entry, so there's still a chance a dogmatic CO may deny (unless of course she actually did state that she was cross-charging to spouse), but I'd think you have a good chance.