Here in the original text, we have another example of the Hebraistic and between an initial present participial clause and its following main clause. Such usage is found elsewhere in the original text, as noted in the discussion under Alma 2:30. Joseph Smith, in his editing for the 1837 edition, removed this extra and here in Alma 19:14. In addition, he replaced the repeated subject Ammon with its pronominal form, he. (In his editing of 𝓟, after supralinearly inserting the he, Joseph seems to have forgotten to cross out the original & Ammon; the 1837 edition has only the he, Joseph’s intended emendation.) The critical text will restore the original usage here despite its difficulty.
Summary: Restore in Alma 19:14 the original Hebrew-like use of and after the subordinate present participial clause, plus the full subject noun Ammon: “now Ammon seeing the Spirit of the Lord poured out … and Ammon fell upon his knees and began to pour out his soul in prayer”.