The original text read “all they which should be led out of other countries”. The original phraseology “all they which” is nonstandard. From the perspective of standard English, the use of the subject pronoun they is inappropriate here since the text intends to say that “the Lord hath also consecrated this land (un)to all those who should be led out of other countries”—in other words, we expect an object pronoun form after the preposition to or unto. In the original text, we have related examples with the object pronoun them, such as “all them whom he hath chosen” in 1 Nephi 1:20. This example has the object form them, but when followed by a relative clause such usage is nonstandard. In the Book of Mormon, both they and them, when followed by a relative clause, have normally been edited to those, as here in 2 Nephi 1:5 and in 1 Nephi 1:20. For a complete discussion, see pronominal determiners in volume 3. Here in 2 Nephi 1:5,
Joseph Smith also edited the which to who since the referent was human. For further discussion of this editing, see which in volume 3. The critical text will, of course, restore the original nonstandard phraseology “all they which”.
Summary: In accord with the earliest textual sources, the archaic and dialectal phraseology “all they which” should be restored in 2 Nephi 1:5.