Here the 1830 typesetter switched the order of the modal verb shall and the subject he. This secondary word order, he shall, has persisted in the LDS textual tradition. The 1840 edition restored the original word order, shall he, but probably unintentionally; as a result, the original word order has been retained in the RLDS textual tradition. The critical text will restore the word order found in the two manuscripts, shall he.
In theory, either word order is possible after even so, although elsewhere in the text all examples except one (marked below with an asterisk) have shall before the subject (as originally here in Alma 41:6):
The word order for the nearby example from Alma 41:5 (which was not changed) argues that the 1830 change in Alma 41:6 was accidental.
Summary: Restore the original verb-first word order in Alma 41:6: “even so shall he be rewarded” (as earlier in Alma 41:5: “even so shall he have his reward of evil”).