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 the first part of this verse (“among us” in English translations), translators typically select the inclusive form (including the reader of the gospel) (source: Velma Pickett and Florence Cowan in Notes on Translation January 1962, p. 1ff.). SIL International Translation Department (1999) notes, however that the exclusive pronoun is also a possibility: “Though the pronoun us… refers essentially to mankind in general, it is also a specific historical reference to the incarnation and the fact that Jesus lived on earth at a particular time. In this particular context the pronoun must be in the exclusive first person plural….This usage makes the pronominal reference agree with the following.”
Two translations that reflect that divergence are the Uma translation that uses the inclusive form (source: Uma Back Translation) and the Kankanaey that uses the exclusive pronoun (source: Kankanaey Back Translation).
The second occurrence of the pronoun in this verse (“we have seen his glory” in English) is always exclusive (excluding anyone but Jesus’s eyewitnesses). (Source: SIL International Translation Department (1999))