Question: What was Moroni doing between the battles at Cumorah and his writing of the book of Moroni?
Answer: During that interim, Moroni finished the record of his farther, procured additional plates, and abridged the book of Ether.
There is historical evidence to suggest that he journeyed far beyond Cumorah. For example, on April 25, 1877, Brigham Young and Warren S. Snow rode to the southeast corner of temple hill in Manti, Utah. According to Warren Snow, President Young said on that occasion, “Here is the spot where the Prophet Moroni stood and dedicated this piece of land for a Temple site, and that is the reason why the location is made here, and we can’t move it from this spot; and if you and I are the only persons that come here at high noon today, we will dedicate this ground.”
During this period, Moroni may have interacted with other Nephites, for he writes that the Lamanites “put to death every Nephite that will not deny the Christ” (Moroni 1:2).
Source: 400 Questions and Answers About the Book of Mormon by Susan Easton Black, p. 210.