There is actually some information available, relating to passports, which I guess is valid for other official documents:
https://assets.publishing.service.gov.u ... -birth.pdf
Quote:
"When the authorities of a country change the name of towns, provinces or the
country itself from the original name to a different one, it does so for all official
purposes. It is long-established international practice for passports to reflect
this by recording in passports and travel documents the holder’s place of birth
in its current, official form. For example, Salisbury Rhodesia, is now Harare
Zimbabwe. Please see the table in Annex A of the most commonly
encountered changes of place name. In cases of doubt, examiners should
check an up to date atlas. There is also an up to date list of countries on the
Foreign and Commonwealth Office (FCO) web site."