Many languages distinguish between inclusive and exclusive first-person plural pronouns (“we”). The inclusive “we” specifically includes the addressee (“you and I and possibly others”), while the exclusive “we” specifically excludes the addressee (“he/she/they and I, but not you”). This grammatical distinction is called “clusivity.” While Semitic languages such as Hebrew or most Indo-European languages such as Greek or English do not make that distinction, translators of languages with that distinction have to make a choice every time they encounter “we” or a form thereof (in English: “we,” “our,” or “us”).
For this verse, translators typically select the inclusive form (including Aaron).
In Huautla Mazatec, however, the translators selected the exclusive pronoun (excluding Aaron).
In the Karbi and the Tok Pisin translations, for the first part of the verse the inclusive pronoun is used (including Aaaron) but for the last part (“we do not know what has happened to him” in English) the exclusive pronoun is used (excluding Aaron).
Following are a number of back-translations of Acts 7:40:
Uma: “They said to Harun: ‘Make for us (inc) an idol that we can worship, so that that idol will lead us. Because we (excl.) no longer know what has happened to that Musa who led us (inc) out of Mesir.'” (Source: Uma Back Translation)
Yakan: “Then because Moses was a long time there on the mountain, they said to Harun, ‘Make gods for us (incl.) so that they will go ahead to lead us (incl.). We (incl.) do not know what has happened to Musa who brought us (incl.) out of Misil.'” (Source: Yakan Back Translation)
Western Bukidnon Manobo: “And they said to Aaron, the older brother of Moses, they said, ‘Make us images that can be the gods that we will follow, because as for this Moses, the one who brought us out of Egypt, we do not know where he has gone.'” (Source: Western Bukidnon Manobo Back Translation)
Kankanaey: “When Moses was a long-time on the summit (lit. head) of that-aforementioned mountain, they said to Aaron, ‘Please make gods to lead us, because we (excl.) don’t know what happened to that Moses-(fellow) who led us in our leaving Egipto.'” (Source: Kankanaey Back Translation)
Tagbanwa: “That’s why they asked Aaron, saying, ‘Make images/likenesses of God, that being what will lead us in place of Moises, because we don’t know what has happened to this Moises who caused us to come out of Egipto.'” (Source: Tagbanwa Back Translation)
The name that is transliterated as “Aaron” in English is translated in Spanish Sign Language as “stones on chest plate” (according to Exodus 28:15-30) (Source: John Elwode in The Bible Translator 2008, p. 78ff.)
The name that is transliterated as “Moses” in English is signed in Spanish Sign Language in accordance with the depiction of Moses in the famous statue by Michelangelo (see here). (Source: John Elwode in The Bible Translator 2008, p. 78ff.)
Another depiction in Spanish Sign Language (source: Carlos Moreno Sastre):
The horns that are visible in Michelangelo’s statue are based on a passage in the Latin Vulgate translation (and many Catholic Bible translations that were translated through the 1950ies with that version as the source text). Jerome, the translator, had worked from a Hebrew text without the niqquds, the diacritical marks that signify the vowels in Hebrew and had interpreted the term קרו (k-r-n) in Exodus 34:29 as קֶ֫רֶן — keren “horned,” rather than קָרַו — karan “radiance” (describing the radiance of Moses’ head as he descends from Mount Sinai).
Even at the time of his translation, Jerome likely was not the only one making that decision as this recent article alludes to.