In Metal Gear Solid 5 what language do the soldiers speak in mission 19? I can't interrogate anyone.

By mistake I discarded my Kikongo interpreter. But I have my Russian, Afrikaans and Pashto interpreters on the Support Team.

Also when I check my Support Team detail it says I can translate Kikongo with S rank

If they are speaking Kikongo, is there a way I can find another interpreter? I went on free roam to post #16 in Africa to see if I can find him again with no luck.

NOTE: I can't replay SIDE OP #4, it's greyed out.