Because it's French. It's like they have a different word for everything. It was coronel in French (mistaken for columna which means crown in Latin). The Italians made it right with their word colonello, which the French used, but kept the R sound.
There are over 2100 and by some counts over 3000 languages spoken natively in Africa in several major language families:
There are several other small families and language isolates, as well as obscure languages that have yet to be classified. In addition, Africa has a wide variety of sign languages, many of which are language isolates.
French (le français [lə fʁ̥ɒ̃sɛ] ( listen) or la langue française [la lɑ̃ɡ fʁɑ̃sɛz]) is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the provinces of Quebec, Ontario and New Brunswick (Acadia region) in Canada, the Acadiana region of the U.S. state of Louisiana, the northern parts of the U.S. states of Maine, New Hampshire and Vermont in the New England region, and by various communities elsewhere. Other speakers of French, who often speak it as a second language, are distributed throughout many parts of the world, the largest numbers of whom reside in Francophone Africa. In Africa, French is most commonly spoken in Gabon (where 80% report fluency), Mauritius (78%), Algeria (75%), Senegal and Côte d'Ivoire (70%). French is estimated as having 110 million native speakers and 190 million more second language speakers. Spelling