The changing tides of the war saw Coriantumr and his army flee. They came to “the waters of Ripliancum, which, by interpretation, is large, or to exceed all.” Having the definition added suggests that this name was in Ether’s record, and had to be interpreted so that it could be understood that they came to the shore of a large body of water. In a Mesoamerican view of the geography of the Book of Mormon, this would have been along the Gulf of Mexico.
Most importantly, they move again. This time going southward. Coriantumr’s army “did pitch their tents by the hill Ramah.” That name must also have been on Ether’s original plates. In this case, Moroni doesn’t give an interpretation, but rather a more important definition: “It was that same hill where my father Mormon did hide up the records unto the Lord.” See Mormon 6:6 for the set of records that Mormon buried in Cumorah.
Moroni does not tell us how he knows that the Jaredite hill Ramah is the same as the Nephite hill Cumorah. Perhaps it was revelation. Perhaps it was the symbolic symmetry of the destruction of the two peoples at the same location, for the same sin of turning away from God.