The 1874 RLDS edition replaced the present-tense perfect auxiliary hath with the past-tense had, probably unintentionally. The 1908 RLDS edition restored the correct hath to the RLDS text. In this particular exchange between Zeezrom and Amulek, we have a consistent use of the present tense: “how knowest thou these things … an angel hath made them known unto me”. The critical text will maintain the present-tense hath here in Alma 11:31.
Summary: Retain in Alma 11:31 the present-tense hath, which is consistent with the preceding presenttense knowest in verse 30.