Sirkku Skousen (personal communication) has raised the possibility that the text here should read in the plural, as “some souls”. Later on in the verse we have a use of the single word some where the meaning is plural:
In English, the determiner some can occur with the plural souls, but the only example in the Book of Mormon reads “some few of their souls”:
Of course, this is not some souls.
Elsewhere there is evidence that the singular some soul is possible. Later on, Alma refers to his own desire to save his fellow beings (just like Ammon does in Alma 26:30):
Both Alma 26:30 and Alma 29:9 are extant in 𝓞 for the phrase some soul, so the singular usage appears to be fully intended. The critical text will accept the use of some soul in the Book of Mormon text.
Summary: Retain the singular usage some soul in Alma 26:30 and Alma 29:9, the reading of 𝓞 in both instances.