I'm not surprised you misunderstand. You do that a lot with bible verses and stories.Yet your god spoke directly to Jephthah several times and could have easily stopped him with but a word. Worse after Jephthah roasted his daughter for your god he was proclaimed a hero from then after. He is praised not vilified even in the New Testament and in all churches to this day.
There is a point to Judges 11. There's also deep meaning to it. Can you guess what it is?(since you don't know, make a guess)