In this indirect quote from Lehi, Joseph Smith’s editing for the 1837 edition increased the use of should. Originally, the verse had only one occurrence of should (in 3). One of Joseph’s should ’s (in 4) was not implemented into the 1837 or any subsequent edition; the original phraseology (“yea even be brought back out of captivity”) has been maintained instead of Joseph’s emended phraseology (“yea even should be brought back out of captivity”). It is possible that this lack of change in the text was influenced by the edited text in 2, for which no should was inserted (“that many be carried away captive”). In fact, it is possible that Joseph actually intended the clause in 2 to read “that many should be carried away captive”, but he ended up inserting only the be. Finally, at the end of this indirect quote (in 6), the original infinitive clause was converted to a finite clause by adding the subject they and by again inserting the modal verb should.
The original text here in 1 Nephi 10:3 starts out with the past-tense verb form were, which seems strange because Lehi is prophesying of the future. Yet such examples of tense shifting are common in English discourse (as in the sentence “he told me that he was coming tomorrow”). Here in 1 Nephi 10:3, the tensed verb forms were and are occur in the two after-clauses (in 2 and 5), while should occurs in the main clause in 3 (“they should return again”). Generally speaking, this kind of construction has been left unedited elsewhere in the Book of Mormon text. Consider, for instance, the indirect quote later on in 1 Nephi 15:20. In this instance, Nephi is referring to a prophecy of Isaiah’s about the future of the house of Israel. As in 1 Nephi 10:3, the were is found in the after-clause, while should is found in the following main clause:
The last editing change in 1 Nephi 10:3 (in 6) fulfills several purposes. With the addition of the subject they, the second after-clause is now followed by a main clause, which conforms with the previous after-clause. And by adding the should, we now have a modal verb in two main clauses, which conforms with the use of should in the main clause of 1 Nephi 15:20. A third purpose of the editing has been to remove the nonstandard use of the infinitive clause (“to possess again their land of inheritance”). Nonetheless, the original infinitive clause is readily understood.
The critical text will, of course, follow the earliest reading for 1 Nephi 10:3, including the nonstandard use of the infinitive clause at the end of the indirect quote.
Summary: Restore the original verb forms in 1 Nephi 10:3 since the edited changes favoring should were unnecessary.