In the first printing of the 1852 LDS edition, the perfect have in “I have beheld” was accidentally omitted. In the second printing, the have was supplied, probably by reference to the 1840 edition. Although the simple past-tense beheld will work, the surrounding text is in the perfect (“which thou hast done” and “how thou hast ... declared the word”). The original “I have beheld” will be maintained in the critical text.
Summary: Maintain the perfect “I have beheld” in Helaman 10:4, the reading of the earliest extant source (the printer’s manuscript).