Here the earliest text has two instances of the third person singular present doth for plural subjects, his angels in the first case and they in the second. For another example where an original doth is followed by a plural subject, see under Helaman 5:38 (which originally read “what doth all these things mean”). Here in Moroni 7:17, Joseph Smith changed the second instance of doth to do in his editing for the 1837 edition but left the first instance unchanged. The corresponding change to do for that instance was made in the editing for the 1920 LDS edition. The critical text, of course, will restore both instances of original doth since the third person singular ending -(e)th occurred very often with plural subjects in the original text (as explained under the clause “Nephi’s brethren rebelleth against him” in the 1 Nephi preface or, more generally, under infl tional endings in volume 3).
Summary: Restore the two instances of doth in Moroni 7:17 since verb forms ending in -(e)th often occurred with plural subjects in the original text of the Book of Mormon.