Here the 1837 edition accidentally replaced the motion preposition into with in. Of course, in can be used as a motion preposition in English, as in “he came in the house”. Yet the Book of Mormon text typically avoids such motion uses of in, as explained in some detail under 1 Nephi 4:33. Also under that passage, I list a number of instances in the history of the text where a correct into has been replaced by in. Based on usage elsewhere in the text, into is definitely correct here in Alma 60:30; this passage refers to entering the land of Zarahemla, not traveling around in it. The 1908 RLDS edition restored the original into here, the reading in 𝓟 (𝓞 is not extant).
Summary: Restore the preposition into in Alma 60:30 (“even into the land of Zarahemla”), the reading in 𝓟; usage elsewhere in the text strongly supports the preposition into in references to entering a land.