The Greek term that is translated as “angel” in English versions in this verse is translated into the Khmer Standard Version (2005) as as “soul” because people believe that the “soul” of a dead person can come back and knock on the door asking for food any time up to 7 days after death.
The Greek that is translated as “fool” (in Matthew 5:22) or “insane” is translated in Mairasi as “(your/their) vision has dried up.” The opposite (“sane”) is “vision is well-split” (see right mind / sound-minded).
The Greek that is translated as “You are out of your mind!” or similar in English is translated in Low German idiomatically as Du büst wull nich bi Trost lit. “you can’t even be comforted anymore” (translation by Johannes Jessen, publ. 1933, republ. 2006).
Apali: “God’s one with talk from the head” (“basically God’s messenger since head refers to any leader’s talk”) (source: Martha Wade)
Michoacán Nahuatl: “clean helper of God” (source: B. Moore / G. Turner in Notes on Translation 1967, p. 1ff.)
Nyongar: Hdjin-djin-kwabba or “spirit good” (source: Warda-Kwabba Luke-Ang)
Wè Northern (Wɛɛ): Kea ‘a “sooa or “the Lord’s soldier” (also: “God’s soldier” or “his soldier”) (source: Drew Maust)
Iwaidja: “a man sent with a message” (Sam Freney explains the genesis of this term [in this article): “For example, in Darwin last year, as we were working on a new translation of Luke 2:6–12 in Iwaidja, a Northern Territory language, the translators had written ‘angel’ as ‘a man with eagle wings’. Even before getting to the question of whether this was an accurate term (or one that imported some other information in), the word for ‘eagle’ started getting discussed. One of the translators had her teenage granddaughter with her, and this word didn’t mean anything to her at all. She’d never heard of it, as it was an archaic term that younger people didn’t use anymore. They ended up changing the translation of ‘angel’ to something like ‘a man sent with a message’, which is both more accurate and clear.”)
Following are a number of back-translations of Acts 12:15:
Uma: “They said to her: ‘You (sing.)’re crazy!’ But she repeatedly said that it was indeed he. That is why they said to her: ‘That’s not Petrus. That’s his angel.'” (Source: Uma Back Translation)
Yakan: “‘Perhaps you are out-of-your-mind,’ they said to Roda. But she kept repeating that it was really true Petros was there. Then they said, ‘That is his angel.'” (Source: Yakan Back Translation)
Western Bukidnon Manobo: “And her companions said to her, ‘You’re crazy.’ But Rhoda insisted saying, ‘No, it really is Peter.’ And they said, ‘It’s not Peter, but rather it is the angel of God that watches him.'” (Source: Western Bukidnon Manobo Back Translation)
Kankanaey: “‘Why, you (sing.) are foolish indeed,’ they said. When she kept-on-insisting that it was true, they said, ‘It’s probably his angel.'” (Source: Kankanaey Back Translation)
Tagbanwa: “But they didn’t believe. In fact they said to that woman/girl that she was crazy. But she said emphatically, ‘It really is he!’ They were saying, ‘Maybe it’s just his angel.'” (Source: Tagbanwa Back Translation)
Teutila Cuicatec: “They told her: ‘You are crazy, girl’ But the girl said it was really him. Then they said: ‘It is not him. Probably it is the angel that looks after him.'” (Source for this and one above: Viola Waterhouse in Notes on Translation August 1966, p. 86ff.)