Here the original manuscript reads in the present tense, “and ye also behold”. When he copied from 𝓞 into 𝓟, Oliver Cowdery replaced behold with the past-tense beheld. The surrounding text is in the present perfect, such as “my brother hath proven” in the following clause and “we have beheld” in the preceding sentence:
This preceding instance of the past participle beheld in verse 5 may have prompted the change to the past-tense beheld in verse 6. The critical text will restore the original present-tense behold here in Alma 34:6. For further discussion of the mix-ups between behold and beheld, see under Jacob 5:37.
Summary: Restore in Alma 34:6 the simple present-tense reading behold found in the original manuscript; the present-tense usage is consistent with the present perfect in the surrounding text.