Normally, you always have a question about neighboring countries (where appropriate). That is actually missing here, and would probably have been more difficult.
I tried Congo for the ethnicity, because I had a faint idea that it was the same as the country name. Wouldn't have crossed my mind to spell it with a K. My disappointment is immeasurable and my day is ruined. I think, since it is a spelling difference due to differing languages, and since C and K are exchangable sounds in English in this instance at least, more leniency would be highly appreciated!
But apparently Yuca is not a spelling error or alternate spelling (or english word) for Yucca.
In Germany, it is Kongo. Also in the native languages. Repubilika ya Kôngo (Kongo)
Republíki ya Kongó (Lingala)