Here the end of Alma 53 (the end of chapter XXIV in the original chapter system) has an instance of etc. that appears to be completely gratuitous. Note that the etc. comes right after “and thus ended the twenty and eighth year of the reign of the judges over the people of Nephi”. One wonders what else could have happened in that year after the year had ended! It is not surprising then that this example of etc. was removed from the LDS text by the editors for the 1920 edition. That edition removed quite a few cases of etc., although in other cases we usually find that the etc. can be identified with specific information. See, for instance, the discussion regarding the original etc. in Mosiah 8:8, Alma 3:17, and Alma 43:8.
One way to look at this unexpected instance of etc. here at the end of Alma 53 is to realize that there would have been many other things written in the original record, the large plates of Nephi, that Mormon chose not to record in his abridgment of the Nephite history. A similar example of using etc. to stand for general indeterminate information is found at the end of Alma 49 (at the end of chapter XXI in the original chapter system); in fact, it occurs twice in the summarizing last verse:
For further discussion, see under that passage.
The use of etc. to stand for general abridgment of the text can also be found at the very end or near the end of the prefaces that typically precede the beginning of books in the Book of Mormon:
In the prefaces, the etc. indicates that there is more in the actual account that follows. On the other hand, an etc. at the end of an original chapter in the account proper can indicate that there is more information in the original unabridged account. The critical text will therefore restore the etc. here at the end of Alma 53 since it is intended and can be explained as an indicator of abridgment.
Summary: Restore the etc. in Alma 53:23 since it is intentional and appears to refer to additional information in the original record that Mormon chose not to cover in his abridged record.