Complex sentence: Rudolf Koeckert allowed Leopold Nowak to put his group's phrasing and dynamics into the Gesamtausgabe parts, but the Gesamtausgabe score contains only those markings in Bruckner's hand.
Split into simpler sentences: Rudolf Koeckert allowed Leopold Nowak to put his group's phrasing and dynamics into the Gesamtausgabe parts. However, the Gesamtausgabe score contains only those markings in Bruckner's hand.