That kiswahili is de facto official language is not in dispute.
From the en.wikipedia.org
Kiswahili is the Swahili word for the Swahili language, and this is also sometimes used in English.
From the en.wikipedia.org
Kiswahili is a trade language, in which people learn enough to exchange greetings, bargain in markets and ask for directions, when they don't speak a common native language.
From the en.wikipedia.org
More examples
A Bantu language
Swahili (or Kiswahili) is a Bantu language spoken by various ethnic groups that inhabit several large stretches of the Indian Ocean coastline from northern Kenya to northern Mozambique, including the Comoros Islands. ...
Noun, Swahili (ki- (language) + swahili (the Swahili region)).