I'd recommend "Harp of Glory - Enzira Sebhat" published by St. Vladimir Seminary Press (
http://www.svspress.com/)& #39 in the Popular Patristics Series; ISBN 978-0-88141-054-9
It's "a major hymn sounding the praises of the Theotokos, from the heart of the Ethiopian Orthodox Church in its Golden Age...it approaches closely to the character and genius of the Byzantine Akathist to the Mother of God...is so profoundly rooted in a different indigenous experience that it surely deserves the title of "An African Akathist."