Following are a number of back-translations of Acts 21:4:
Uma: “There we (excl.) visited the followers of Yesus and stayed with them a week. From the leading of the Holy Spirit, those companions of ours(excl.) in Tirus warned Paulus not to continue on to Yerusalem.” (Source: Uma Back Translation)
Yakan: “We (excl.) found there some disciples of Isa and we (excl.) stayed with them for one week. Because they had been made-to-understand/explained by the Spirit of God, so they told Paul not to proceed to Awrusalam.” (Source: Yakan Back Translation)
Western Bukidnon Manobo: “We found some disciples there, and we stayed there with them for a week. They were inspired by the Holy Spirit, therefore they warned Paul that he should not go on to Jerusalem.” (Source: Western Bukidnon Manobo Back Translation)
Kankanaey: “When we (excl.) then came-upon some disciples of Jesus, we (excl.) spent-a-week staying-with them. They repeatedly warned Pablo that he ought not to continue going to Jerusalem, because the Holy Spirit had-made-known to them that he would be hardshipped there.” (Source: Kankanaey Back Translation)
Tagbanwa: “When we (excl.) came ashore there, we (excl.) searched for believers from there. Well, because it had been made known to them by the Espiritu Santo that when Pablo arrived in Jerusalem, he would really be caused suffering by the people from there, they kept saying to him that he not continue on. But Pablo wouldn’t let himself be disuaded. One week is how long we (excl.) were there,” (Source: Tagbanwa Back Translation)
Many languages distinguish between inclusive and exclusive first-person plural pronouns (“we”). (Click or tap here to see more details)
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 exclusive form (excluding the addressee).
Source: Velma Pickett and Florence Cowan in Notes on Translation January 1962, p. 1ff.
The Greek that is often translated as “disciple” in English typically follows three types of translation: (1) those which employ a verb ‘to learn’ or ‘to be taught’, (2) those which involve an additional factor of following, or accompaniment, often in the sense of apprenticeship, and (3) those which imply imitation of the teacher.
Following are some examples (click or tap for details):
Waorani: “one who lives following Jesus” (source: Wallis 1973, p. 39)
Ojitlán Chinantec: “learner” (Source: M. Larson / B. Moore in Notes on Translation February 1970, p. 1-125.)
Javanese: “pupil” or “companion” (“a borrowing from Arabic that is a technical term for Mohammed’s close associates”)
German: Jünger or “younger one” (source for this and one above: Reiling / Swellengrebel)
Nyongar: ngooldjara-kambarna or “friend-follow” (source: Warda-Kwabba Luke-Ang)
In Luang several terms with different shades of meaning are being used.
For Mark 2:23 and 3:7: maka nwatutu-nwaye’a re — “those that are taught” (“This is the term used for ‘disciples’ before the resurrection, while Jesus was still on earth teaching them.”)
For Acts 9:1 and 9:10: makpesiay — “those who believe.” (“This is the term used for believers and occasionally for the church, but also for referring to the disciples when tracking participants with a view to keeping them clear for the Luang readers. Although Greek has different terms for ‘believers’, ‘brothers’, and ‘church’, only one Luang word can be used in a given episode to avoid confusion. Using three different terms would imply three different sets of participants.”)
For Acts 6:1: mak lernohora Yesus wniatutunu-wniaye’eni — “those who follow Jesus’ teaching.” (“This is the term used for ‘disciples’ after Jesus returned to heaven.”)
Source: Kathy Taber in Notes on Translation 1/1999, p. 9-16.