Here in the original manuscript, Oliver Cowdery originally wrote striplings. He seems to have expected stripling as a noun rather than as an adjective (replacing, but only momentarily, stripling soldiers with striplings). But Oliver immediately caught his error in 𝓞 and erased the plural s at the end of striplings. The only other example of stripling in the Book of Mormon text also occurs as an adjective: “and the remainder I took and joined them to my stripling Ammonites” (Alma 56:57). According to the Oxford English Dictionary, the word stripling appears to derive from the meaning ‘one who is slender as a strip’ (that is, ‘one whose figure is not yet filled out’). Under definition 1 for stripling, the OED describes the noun as a youth who is “just passing from boyhood to manhood” and provides citations from the late 1300s into the 1800s. The word stripling occurs once (as a noun) in the King James Bible, namely, when king Saul wants to find out who this young man is that has challenged Goliath: “inquire thou whose son the stripling is” (1 Samuel 17:56). The use of stripling as a modifier, originally nominal but now having become adjectival, is described under definition 2 in the OED, with citations from the 1500s into the 1800s (such as the citation from Alexander Pope in 1725 of “gay stripling youths”). Today the vast majority of speakers are totally unfamiliar with the word stripling and can only guess at its meaning in the Book of Mormon.
Summary: Maintain in Alma 53:22 and Alma 56:57 the two instances of stripling as a noun modifier.