Only birthday and anniversary is to less for a contact. More dates are available on Android and iOS. When I set a day of death there, I cannot see this date in KDE contacts. Th problem is maybe a non-standard because in Android a day of death is saves as follows in a VCF line: X-ANDROID-CUSTOM:vnd.android.cursor.item/contact_event;2012-11-13;0;Day of Death;;;;;;;;;;;; Maybe it is possible to also add "manual dates" with an inidividual title.