For both cases of they in 2 Nephi 10:21–22, Joseph Smith’s editing for the 1837 edition, as indicated on the printer’s manuscript, was not implemented in that edition. In the first example, Joseph overwrote the ey of they with ose. In the second example, he overwrote only the y of they with se. In the first case, the intended change was obviously they to those. In the second case, the stated change is they to these, but it is quite possible that Joseph Smith’s intended change was actually they to those since there are no other occurrences of “all these who” in the current Book of Mormon text—but there are 56 of “all those who” (most of which were created as a result of Joseph Smith’s editing for the 1837 edition). Nonetheless, “all these who” could still work since Jacob has just been discussing those of scattered Israel who are upon the isles of the sea.
In accord with Joseph Smith’s corrections in 𝓟, the editors for the 1908 RLDS edition implemented those changes. Interestingly, they interpreted the second change as the same as the first one (namely, of they to those). The editing in the LDS text has been different. In the LDS text, both cases of original they were replaced by them in the third printing (in 1907) of the 1905 Chicago edition, but the second of these changes was not followed by the subsequent 1911 largeprint Chicago edition. The 1920 edition ended up making sure both changes of they to them were implemented in the text. For further discussion, see pronominal determiners in volume 3.
Note, by the way, that in his editing of 𝓟 for the 1837 edition, Joseph Smith changed the two instances of which to who. But unlike the editing of the two pronouns they, the edited relative pronoun who was implemented both times in the 1837 edition. Of course, the critical text will restore both instances of the original “they which” here in 2 Nephi 10:21–22.
Summary: Restore the two original instances of “they which” in 2 Nephi 10:21–22.