The 1858 Wright edition added the before “things temporal” but not before “things spiritual”, thereby violating the original parallelism in this conjoining of prepositional phrases. The 1908 RLDS edition restored the original reading. As discussed under Alma 32:3–4, either phraseology, “as to things” or “as to the things”, is possible, although the first is considerably more frequent in the Book of Mormon text. For each case of “as to (the) things”, the critical text will follow the earliest extant reading, thus “both as to things temporal and to things spiritual” here in Helaman 14:16.
Summary: Maintain in Helaman 14:16 the original parallelism of the phrase “as to things temporal and to things spiritual” (that is, without a the before things in both cases).