Isaiah 12:1 (King James Bible) and thou comfortedst me
For the past-tense comforted, the original Book of Mormon text used the reduced inflectional ending -st, the same one as in the corresponding King James passage. The 1852 LDS edition inserted an e to produce the fuller inflectional ending -est. For modal verb forms like would(e)st and should(e)st, the original Book of Mormon text has preferred the reduced form -st over the fuller -est. For discussion of the inflectional ending -(e)st for these two modal verbs, see under 1 Nephi 20:5.
Summary: In 2 Nephi 22:1 maintain comfortedst (the original reading in the Book of Mormon), which agrees with the King James reading.