Question: Did Jephthah sacrifice his daughter in Judges 11?
Answer: NO.
Jephthah did not sacrifice his daughter as a burnt offering; that was never his intention. Rather, he vowed to dedicate her to Yahuwah's service - which meant that she would remain a virgin. This made Jephthah upset because she was his only child (Judges 11:34), which meant he would have no legacy. When read alongside Leviticus 27 and the laws about vows, the text becomes clearer. Some of the words, also, were apparently not translated as they should have been.
The first key verse:
Then it shall be, that whatsoever cometh forth of the doors of my house to meet me, when I return in peace from the children of Ammon, shall surely be [Yahuwah’s], and I will offer it up for a burnt offering [H5930]. (Judges 11:31)
H5930 is not always indicative of a burnt offering. It can also mean "stairs, as ascending", which carries the connotation of something moving upward or directed to heaven.
Examples:
And when the queen of Sheba had seen all Solomon's wisdom, and the house that he had built, And the meat of his table, and the sitting of his servants, and the attendance of his ministers, and their apparel, and his cupbearers, and his ascent [H5930] by which he went up unto the house of [Yahuwah]; there was no more spirit in her. (1 Kings 10:4-5)
And there were seven steps to go up [H5930] to it, and the arches thereof were before them: and it had palm trees, one on this side, and another on that side, upon the posts thereof." (Ezekiel 40:26)
The second key verse:
That the daughters of Israel went yearly to lament [H8567] the daughter of Jephthah the Gileadite four days in a year. (Judges 11:40)
H8567 is not indicative of sadness; it means, "(...the idea of attributing honor); to ascribe (praise), that is, celebrate, commemorate."
With the above in mind, read the entire story. Jephthah did not sacrifice his daughter as a burnt offering.
29Then the Spirit of [Yahuwah] came upon Jephthah, and he passed over Gilead, and Manasseh, and passed over Mizpeh of Gilead, and from Mizpeh of Gilead he passed over unto the children of Ammon.
30And Jephthah vowed a vow unto [Yahuwah], and said, If thou shalt without fail deliver the children of Ammon into mine hands,
31Then it shall be, that whatsoever cometh forth of the doors of my house to meet me, when I return in peace from the children of Ammon, shall surely be [Yahuwah’s], and I will offer it up for a burnt offering [ascending/heavenly dedication].
32So Jephthah passed over unto the children of Ammon to fight against them; and [Yahuwah] delivered them into his hands.
33And he smote them from Aroer, even till thou come to Minnith, even twenty cities, and unto the plain of the vineyards, with a very great slaughter. Thus the children of Ammon were subdued before the children of Israel.
34And Jephthah came to Mizpeh unto his house, and, behold, his daughter came out to meet him with timbrels and with dances: and she was his only child; beside her he had neither son nor daughter.
35And it came to pass, when he saw her, that he rent his clothes, and said, Alas, my daughter! thou hast brought me very low, and thou art one of them that trouble me: for I have opened my mouth unto [Yahuwah], and I cannot go back.
36And she said unto him, My father, if thou hast opened thy mouth unto [Yahuwah], do to me according to that which hath proceeded out of thy mouth; forasmuch as [Yahuwah] hath taken vengeance for thee of thine enemies, even of the children of Ammon.
37And she said unto her father, Let this thing be done for me: let me alone two months, that I may go up and down upon the mountains, and bewail my virginity, I and my fellows.
38And he said, Go. And he sent her away for two months: and she went with her companions, and bewailed her virginity upon the mountains.
39And it came to pass at the end of two months, that she returned unto her father, who did with her according to his vow which he had vowed: and she knew no man. And it was a custom in Israel,
40That the daughters of Israel went yearly to lament [celebrate / ascribe honor to] the daughter of Jephthah the Gileadite four days in a year. (Judges 11:29-40, KJV)