In this passage the 1920 LDS edition deleted the and before “he also knowing”. The apparent intent of this editing was to connect the initial when-clause to the immediately following finite clause (“he ... feared”). However, this independent clause should be considered parenthetical, with the result that the initial when-clause is actually completed by the subsequent therefore-clause. Such an analysis suggests that this long intervening clause should be separated off by dashes (or parentheses) from the rest of the sentence:
Of course, the syntax here is complicated no matter what is done. The proposed dashes (or parentheses) do, however, capture the original intent of the passage. For a similar complex example involving a long parenthetical clause, see the discussion under 2 Nephi 25:16–17.
Summary: Restore in Alma 22:22 the original and that immediately precedes the long parenthetical clause “he also knowing the hardness of the hearts of the people feared lest that a multitude should assemble themselves together and there should be a great contention and a disturbance among them”; the initial when-clause in this passage is completed by the final therefore-clause.