vcard version 4.0
When importing a vcard not all data is preserved in the contact info.
Language options: when a vcard has a property multiple times with different languages, only one is preserved. This Selection currently does not follow the PREF parameter. (Bug?)
N is currently overwritten by FN, my vcard had both defined, only FN was used by kaddressbook. (Bug?)
vcard extension RFC 6715 provides more Standards, one is EXPERTISE this should be preferred over custom Properties (X-KADDRESSBOOK-X-Profession)
To sum it up, my wish would be that all data is preserved. If not all is shown, that’s OK but unknown or duplicate properties should be preserved in the custom fields.