Does the Eastern Catholic Church maintain the tradition of not permitting musical instrumentation such as organ music, piano, or guitar music, during the Divine Liturgy?
Most Eastern Catholic Churches do not use any musical instrumentation during the Divine Liturgy. The Ethiopian Catholics do use drums, however.
The reason that we don’t use instrumentation is because of our particular perspective on the Liturgy. We try very hard to model our liturgical worship on the Liturgy being celebrated in heaven, as it is depicted in Biblical books such as Revelation. In such texts the heavenly Liturgy is celebrated using primarily the human voice.