My Irish American/Swamp Yankee grandparents attended a Lebanese Church in Quincy Massachusetts. I enjoyed this article, well done.
That would be a Maronite Catholic Church. There are 7 Maronite Churches in MA: Brockton, Springfield, Lawrence, New Bedord, Fall River, Jamaica Plain and Worcester.
I am Roman Catholic but, like your grandparents, also attend a Maronite Church. The liturgy is older than that of the Latin Church, tracing its heritage to the city of Antioch where Peter served as bishop before proceeding to Rome.