as you noted, is the old name of the DR of Congo. It comes from the word "zaire" which is the Portugese variant of the Bantu
nzari = river.
The first European explorers thought the river Congo was named Zaire. It was only later that they learned that
nzari was the actual word for "river" and the name of that particular
nzari was Congo.
[Also DR = democratic republic, though my limited experience shows that when a country puts Democratic in its name, one has to be suspicious]
For more African Geographic Names:
http://kalamumagazine.com/african_country_name_origin.htm
Osbaldo and
Osvaldo are the Spanish equivalents of
Oswald. Oswaldo is not Spanish for sure, but I have no clue as to what it is