The Gerontology Wiki is not going to be Wikipedia, forbidding the use of flags to indicate places of birth and death.
However, the default (standard) value should be text first, with flags added as an additional visual element.
We also need to be concerned regarding whether the person identified with the flag actually does identify with the particular flag.
Common sense should be used here.
I am recommending:
Flags for the place of birth should reflect the flag then in use at the time of the birth. Thus, Emile Fourcade was born in 1884 in French Algeria, not Algeria.
Flags for the place of death/current residence should be easier to clarify...in almost all cases, the place a supercentenarian died or resides coincides with their citizenship status. Exceptions to the rule can be notated with a footnote.
That said, we also should decide whether to put flags in the same column as the written text, or a separate column.