You should know that in the Vatican Directory titled, Ad Totum Eccesiam, 14 May, 1967, Chapter IV,Section C, 1,47 it makes it quite clear that Catholics, East and West, fulfill their "Sunday Obligation" when they attend an Orthodox Divine Liturgy. I would suggest you read this enlightening document, especially part 1 of Section C.
I find it unfortunate that these documents do not make it down to the faithful,even in a synthesized form. 1967 was 45 years ago! Lord, have mercy.
Canon Law of 1983 actually says that a Latin Catholic fulfils their obligation by attending a Liturgy(Mass) of any Catholic Rite.
Curiously, an equivalent law does not exist in the CCEO. It just says that how obligations are fulfilled are up to the definition by the synods of the respective sui juris. So if your Eastern Catholic bishops say you can go to an Orthodox Divine Liturgy under certain circumstances, or under any circumstance, then you can. If they say you cannot, then you cannot (by which I mean fulfill your "obligation").
