What about their work efficiency!??
And somehow (by coincidence or sheer luck) all those nationalities you just mentioned are French speakers. So at least they have a common means of communicating. Their mode of instructions in their tertiary education was FRENCH...they will learn English then just to accomodate them at their work environment or otherwise.
Most of those who do not speak English do not work with local offices, they are at the Rwanda genocide blah blah, or interpreters for sam languages...TUSIDANGANYANE!!!!!
KAMA UMEFUNDISHWA KWA KISWAHILI CHUONI THEN UNA HAKI YA KUFANYA KAZI NA KUFANYIWA USAILI KWA KISWAHILI...
MAswali ya mbona wachina mbona warwanda...hayana msingi!
Thirdly, English has become the 'world' language...waangalie hata hao warwanda wako in their country wameamua kubadili mfumo waofrom French to English...SHTUKA!