In this passage, we have some minor variation in grammatical number for two of the conjoined nouns. In the first case, the 1911 LDS edition changed swelling to swellings, but the subsequent LDS edition (1920) restored the earlier singular, swelling. In the text there are no other uses in the text of swelling as a noun, only as an adjective:
Here in Helaman 13:22, the singular swelling is immediately followed by plural conjuncts (“envyings, strifes”), which suggests that the plural swellings is possible. Indeed, the 1911 reading was very likely influenced by those two following plural nouns. Since either swelling or swellings is theoretically possible, the critical text will follow the singular swelling here in Helaman 13:22.
Another possibility here in Helaman 13:22 is that the word swelling is actually an adjective (as in the two Alma passages), so that what we have here is “great swelling envyings”. The 1830 typesetter decided otherwise since he placed a comma between swelling and envyings. He was undoubtedly led to this conclusion by the preceding gerund, boasting; note the parallelism of “unto boasting and unto great swelling”. Moreover, the word envying(s) is never modified by an adjective elsewhere in the text, thus Mormon 8:28: “even to the envying of them who belong to their churches”. (All other instances of envying(s) in the text are listed below in the next paragraph; in none of these cases is envying(s) modified by an adjective.)
The second case of variation in this passage involves the plural envyings. In the first printing of the 1852 LDS edition, the word was set as the singular envying. In that instance, the preceding singular swelling was the probable source for the mis-setting of envyings as envying. In the second printing of that edition, the plural envyings was restored, probably by reference to the 1840 edition. Elsewhere in the earliest text, in conjuncts involving envying(s), all examples but one are in the plural (the singular one is marked below with an asterisk):
(See the discussion under Mormon 8:36 for the possibility that the singular envying is an error for envyings.) In any event, the critical text will maintain the plural envyings here in Helaman 13:22 since it is the earliest reading.
Summary: Maintain in Helaman 13:22 the singular swelling and the plural envyings in the list of conjuncts (“and unto great swelling / envyings strifes malice persecutions and murders”); in this case, both 𝓟 and the 1830 edition agree, which argues that 𝓞 (not extant here) read the same.