Yugoslavia would be awful, it is a state by far the most famous for collapsing into internal genocide twice during 50 years, it overshadows all other claims to fame of theirs. Serbia is a very good medieval culture candidate (very long living state with good documentation and plenty of achivements) with Croatia and Bośnia being somewhat less exciting medieval cultures, and sadly that would be it for this area. Well, you could also do an industrial Serbia (1813 - 1918) as a militarist state.
Imho it will be
African country - agrarian or aestethe
America - merchant
Brazil - agrarian or aestethe
China - builder
India - agrarian or aestethe
Japan - aestethe, merchant or scientist
Korea - merchant or scientist
Soviet - expansionist
Sweden - scientist
Vietnam - militarist
Other possible choice would be Turkey - aestethe.
I would be really disapointed if Sweden for into modern era, because this way you make it unable to enter early modern or industrial eras when it was a great candidate, whereas in the modern era you could as well put Finland, Switzerland (scientist) or Czechoslovakia (builder) from Europe.
I also really hope we'll get Nigeria or Kenya instead of Ethiopia, because not only (let's be honest) Ethiopia in the period 1920 - 2020 was a miserable country, but also it can be put much more gloriously in the medieval, early modern or industrial eras.
Why have we got Zulu in the industrial era but not Ethiopia which actually avoided colonization succesfully - amazes me