In this passage there is some question about whether it were is actually necessary (the 1892 RLDS edition deleted it, although perhaps unintentionally). It is definitely unexpected in normal English; the phraseology we expect is “and the people were as numerous almost as the sand(s) of the sea” (or, more usually, with almost right after the verb: “and the people were almost as numerous as the sand(s) of the sea”). Yet the additional it were is actually characteristic of the Book of Mormon text, including these examples that deal with the numerousness of peoples:
We might wonder also about whether the text should read “the sand of the sea” (as in 1 Nephi 12:1) or “the sands of the sea” (as in Alma 2:27). Here in Mormon 1:7, scribe 2 of 𝓟 initially wrote the plural sands, which Oliver Cowdery later corrected to the singular sand, which agrees with the 1830 reading. Elsewhere in the Book of Mormon (as seen in the discussion under Alma 2:27), we have only one example of the plural sands (namely, in Alma 2:27). Otherwise, we have only the singular sand —namely, in 1 Nephi 12:1, here in Mormon 1:7, and in three quotes from the King James Bible: 1 Nephi 20:19 (Isaiah 48:19), 2 Nephi 20:22 (Isaiah 10:22), and 3 Nephi 14:26 (Matthew 7:26). The King James Bible uses only the singular sand; in particular, it has ten occurrences of “the sand of the sea”. All of this suggests that the plural sands in Alma 2:27 could be a mistake for the singular sand. See under that passage for discussion. Here in Mormon 1:7 the critical text will maintain the singular sand, the 1830 reading as well as the corrected reading in 𝓟.
Summary: Maintain in Mormon 1:7 the use of it were in “almost as it were the sand of the sea”; the Book of Mormon actually favors the use of it were in this construction; the singular sand should also be maintained since the text prefers the singular (the only example of the plural sands is in Alma 2:27).