In that case, the supralinear of was written in 𝓟 with heavier ink flow; again the correction probably occurred when Oliver proofed 𝓟 against 𝓞. As explained under Alma 53:6, either reading, with or without the of, for “city (of ) Mulek” is possible. In each case, the critical text will follow the earliest extant reading, thus the corrected reading in 𝓟 for Helaman 5:15 and the reading in 𝓞 for Alma 53:2.
Summary: Maintain the occurrence of of for “the city of Mulek” in Helaman 5:15; the corrected of is very likely the reading in 𝓞 (which is not extant here); also maintain the of in Alma 53:2, which is extant in 𝓞.