I think most of the unknown dates can be narrowed down to 2 decades (ie 1980s and 1990s).
Encode these as "199x" or "198x" instead of "1900".
While iterating on this, the json files can be written out with these decades filtered to write out "1900" instead.
Then the swift app can be updated to read "199x". Once that is published, then the generator can write out "199x".
I think most of the unknown dates can be narrowed down to 2 decades (ie 1980s and 1990s).
Encode these as "199x" or "198x" instead of "1900".
While iterating on this, the json files can be written out with these decades filtered to write out "1900" instead.
Then the swift app can be updated to read "199x". Once that is published, then the generator can write out "199x".