Here "under" is an idiom that means to be under someone's authority. AT: "Eden ... assisted Kore in the cities of the priests" (See: [[rc://en/ta/man/translate/figs-idiom]])
# They filled offices of trust, in order to give
"Their duty was to give" or "They faithfully gave"
# to their brothers
Here "brothers" is a metaphor for "fellow priests." AT: "to their fellow priests" (See: [[rc://en/ta/man/translate/figs-metaphor]])
# division by division
"group by group"
# to both the important and the unimportant
Here "important" and "unimportant" are used together to mean "everyone." AT: "to everyone, including the important and the unimportant" (See: [[rc://en/ta/man/translate/figs-merism]])
This seems to imply the old and the young. This can be restated to removed the nominal adjectives. AT: "those who are old and those who are young" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-nominaladj]])