Rather than redirecting {{Country data Swaziland}} to {{Country data Eswatini}}, the former template transcludes the latter and passes through all parameters. The linked article will always be "Eswatini", but the displayed name is either "Swaziland" or "Eswatini" based on which of the two templates is used, even in templates that usually have a fixed default display name (such as {{flagcountry}} and {{fb}}). This allows for "Swaziland" to be used in historical contexts without having to also set |name=.

Examples

change
Template Eswatini output Swaziland output
{{flag|SWA}}  Eswatini  Swaziland
{{flagcountry|SWA}}  Eswatini  Eswatini
{{flagicon|SWA}} Eswatini Eswatini
{{fb|SWA}}  Eswatini  Swaziland