Hej is Swedish etc. Oi is from oyez, Latin/French for "hear ye!" Or Listen up! Which is Spanish, Latin languages. Thus showing English as invasions of ceilings and the Norman conquest.
I did read far enough to hear from the Swedish contingent, but stopped halfway through, so maybe this has been already answered.
"Oyez, oyez" was changed to "hear ye, hear ye" in legalese sometime after the Elizabethan period, but I don't know exactly when off hand.