The Beta Israel prayed in Ge'ez, the liturgical language of Ethiopian Christianity, and not in Hebrew. Their services were led not by rabbis but by the kessim, a priesthood of their own, and the shape of the office owed nothing to the rabbinic prayer book that structures Jewish worship almost everywhere else. To a visitor from a synagogue in Europe or the Middle East, very little about a Beta Israel service would have been recognisable except its subject.
The sound was closer to what could be heard across the road. The liturgy was chanted rather than read, accompanied by the kabaro, a double headed drum, by the sistrum, a metal rattle, and by the prayer staff on which the standing clergy leaned and which they struck against the ground to mark the rhythm. Every one of those instruments is also an instrument of Ethiopian Orthodox worship, and the manner of chanting has features in common with it too. The community understood itself as Israelite and ancient; its liturgical toolkit was recognisably Ethiopian.
That combination is what makes the tradition important and what makes it hard to read. It is not a variant of a Jewish liturgy known from elsewhere, because there is no elsewhere it can be compared to. It is a body of practice that has to be interpreted on its own evidence, and the evidence is thin, because nothing about it was written down as music until the twentieth century and the written prayer texts that do survive are not a complete record of what was sung.