What fascinates me about the videos of Bishop Milan is the authentic Eastern-ness of the rubrics - frankly rather unlike what those of us my age grew up with either in the ACROD or the BCC in the 1950's and 60's. I wonder if that was the case in the 1890 -1920 period when our ancestors came to America?
Amongst the Greek Catholics in Halych, Zakarpatia, Slovakia, Hungary, Croatia, Serbia, etc., there has been a concerted effort, supported by Rome by the way, to return to an authentic Eastern Christian praxis, including liturgical celebrations. Bishop Milan was actually a Slovak Roman Catholic religious order priest with a bi-ritual faculty to celebrate according to both the Roman and Byzantine Rites. He ultimately became the ruling bishop because, as I understand it, there were no celibate priests who were considered to be appropriate candidates for episcopacy. I have served with him on two occasions. He is very approachable, and very humble. Liturgically, he carries none of the old "Greek Catholic" baggage. So, they follow the liturgical books as they are written. As to your question about the past, that appears to be a "mixed bag". In my parish in Jessup, Pa., in the 1930's into the 1940's, they had a pastor (forget his name) who was strongly "vostochnik", liturgically. He was followed by a stauunch "latinyak".