These two words basically have the same meaning repeated to emphasize how important Jephthah had became. You can combine the two words. AT: "commander" (See: [[rc://en/ta/man/translate/figs-doublet]])
This is an idiom. Here the phrase "before Yahwheh" means that he repeated his promises as a vow before Yahweh. AT: "When Jephthah was in Mizpah he repeated all of these promises as a vow before Yahweh" (See: [[rc://en/ta/man/translate/figs-idiom]])
