As explained under 1 Nephi 22:4, for certain instances of whither and whether there has been some confusion over which word is intended. Here in Alma 43:22–23, the context clearly indicates that whither, meaning ‘where to’, is the correct reading: Moroni has decided that he will confront the attacking Lamanites; he only wants to know where they are going to attack. Nonetheless, for both these examples of whither, the 1840 edition replaced whither with whether (and the 1858 Wright edition, set from the 1840 edition, continued these two instances of whether). In the 1874 RLDS edition, the correct whither was restored for the first instance, in verse 22, but the incorrect whether was continued in verse 23. In the 1908 RLDS edition, the correct whither in the second instance was finally restored to the RLDS text.
Summary: Maintain whither both times in Alma 43:22–23 since the context clearly indicates that the issue is where the Lamanites are going to attack.