This question is being asked every video of this performance in different names. You could search it or ask someone who knows more about many traditional songs. Basically, the performance is to illustrate the colorful tradition of Ethiopia, not about the title of the song, lyrics, time and year released....
You need to watch the video again. Many of the students in this group are Eritreans and there's no reason to discredit that. Tigrigna, Saho, Afar, Bilen, and Hidereb were all represented, so there's no reason to complain, especially after the hard work the Eritrean students at this school have put in to represent their culture (which they did beautifully).