Complex sentence: The Eastern Catholic Churches are in full communion of faith and of acceptance of authority of the See of Rome, but retain their distinctive liturgical rites, laws and customs, traditional devotions and have their own theological emphases.
Split into simpler sentences: The Eastern Catholic Churches are in full communion of faith. Whilst they accept of authority of the See of Rome, they retain their distinctive liturgical rites, laws and customs, traditional devotions and have their own theological emphases.