The 1874 RLDS edition omitted the perfect auxiliary had in this sentence. Either reading is possible in theory, but the perfect works better here since the Lamanite servants being referred to were those that earlier (in Alma 17:39 –18:3) had told king Lamoni about how Ammon had defended the king’s flocks. The 1908 RLDS edition restored the original had here in Alma 19:15.
Summary: Maintain in Alma 19:15 the original use of the perfect auxiliary had since this is the reading of the earliest text.