Jephthah is rebuking the king of the Ammonites with a rhetorical question. This question can be translated as a statement. AT: "you should have taken them back during that time." or "now it is too late; you should have taken them back long ago." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Jephthah is speaking to the Sihon. Here Jephthah speaks about the Israelites as though they were himself and of the Ammonites as if they were Sihon their king. AT: "The Israelites have not done wrong to your people, but your people are doing us wrong by attacking us" (See: [[rc://en/ta/man/translate/figs-synecdoche]])
This is an idiom. To do someone wrong means to do something wrong to them. AT: "treated you wrongly ... treating me wrongly" or "treated you unfairly ... treating me unfairly" (See: [[rc://en/ta/man/translate/figs-idiom]])