They speak a fictional language called "Hausa" in the comics, But in the MCU all Wakandans speak the "Xhosa" which is a real language.

Hausa

In the comics they speak Hausa, but in the MCU all Wakandans speak the Xhosa, a South African language.

In the MCU they speak Xhosa, which is not a fictional language.

In the MCU, they speak Xhosa, one of the major languages of South Africa. This was in honor of John Kani, who played King T'Chaka, as he is South Africa and this was his native language. Chadwick Boseman studied and learned the language so he could speak in the dialect for his role as Black Panther.

That's commitment right there. He did speak actual Xhosa in Captain America: Civil War if I recall correctly.

I think they speak Xhosa