In the original Book of Mormon text, the verb come frequently takes the simple past-tense form came as its past participle (see the discussion under 1 Nephi 5:1, 4). This same tendency is found with the compound verb overcome. Here in Jacob 5:48 we have two examples, both of which were edited to the standard overcome in the 1837 edition. A third example of this nonstandard usage is found in the book of Alma:
The critical text will maintain the occurrences of the nonstandard past participle overcame here in Jacob 5:48 as well as in Alma 19:6. Also see the general discussion under past participle in volume 3.
Summary: Restore the nonstandard overcame as the past participle in Jacob 5:48 (two times) and in Alma 19:6.