From the Wikipedia page [1]

[Kukurá (Cucurá, Kokura) is a spurious language, fabricated by an interpreter in Brazil.

When Alberto Vojtěch Frič visited Rio Verde, Brazil in 1901 he took with him a Kainguá Indian called Guzmán who said he spoke the language of the local "Chavante" people. A word list was published for the so-called Kukurá language, thought to be an isolate, in 1931. In 1932 Curt Nimuendajú, who had visited the Rio Verde in 1909 and 1913, showed that Guzmán's wordlist consisted half of fake words and half of mispronounced Guaraní. There was no resemblance to the Ofayé language that was actually spoken in the region.