Here the 1830 typesetter pluralized iniquity. When we consider all other examples of “do iniquity” and “do iniquities” in the Book of Mormon text, we consistently find only the singular iniquity, never the plural. In each of these other cases, there has been no change of iniquity to iniquities in any of the textual sources:
Thus in Jacob 2:35 the 1830 typesetter introduced an inconsistency into the text by changing iniquity to iniquities. Most likely, this change was accidental since the typesetter changed no other examples of “do iniquity” to “do iniquities”. The 1908 RLDS edition restored the original singular.
Summary: Restore in Jacob 2:35 the singular iniquity (the reading of the earliest textual source, the printer’s manuscript); there are no examples in the text of the plural “do iniquities”.