Here we see two instances where the correct plural noun judges was replaced by the past participle judged. In the printer’s manuscript, scribe 2 initially wrote “ye shall be judged of this people”, but he immediately corrected the word judged to judges (the correction involves erasure, a sign of immediacy). In addition, the typesetter for the 1902 LDS missionary edition made the same mistake. The error is understandable given that the text has 51 instances of “to be judged” but only 8 of “to be judges” (including this one in 3 Nephi 27:27). Of particular influence here are the two occurrences of “shall ... be judged” in the immediately preceding text:
Of course, here in 3 Nephi 27:27 the obviously intended reading is that the twelve disciples will judge this people. Mormon later explains that not only will these twelve disciples judge the descendants of this people, but they themselves will be judged by the original twelve that Jesus chose during his earthly ministry:
Summary: Maintain the plural noun judges in 3 Nephi 27:27, the 1830 reading as well as the immediately corrected reading in 𝓟.