Chagga Cultural Festival in Moshi/Marangu
The Chagga are confirmed as a real, substantial Bantu ethnic group from the Kilimanjaro Region of Tanzania, the country's third-largest ethnic group, and Moshi and Marangu are genuine Chagga towns on Mount Kilimanjaro's slopes, but no independently confirmed Chagga Cultural Festival by this exact name could be located.
Wikipedia confirms the Chagga, also spelled Chaga, as a Bantu ethnic group from the Kilimanjaro Region of Tanzania and the third-largest ethnic group in the country, with their own documented pre-colonial religion, Chagga religion, known in Swahili as Dini ya Wachagga.