Following are a number of back-translations of 1 John 1:4:

• Uma: “We(excl.) write this so that our (incl.) joy [will] be complete.” (Source: Uma Back Translation)
• Yakan: “I write this to you so that our (incl.) joy will be complete.” (Source: Yakan Back Translation)
• Western Bukidnon Manobo: “And because of that, I am writing to you like this so that our (incl.) joy might be drawn tight.” (Source: Western Bukidnon Manobo Back Translation)
• Kankanaey: “so that we (incl.) will thus be thoroughly happy.” (Source: Kankanaey Back Translation)
• Tagbanwa: “We(excl.) are writing these things so that we can be happy with happiness which has no lack.” (Source: Tagbanwa Back Translation)
• Tenango Otomi: “Now I write these words so that you will more greatly rejoice.” (Source: Tenango Otomi Back Translation)
• Yatzachi Zapotec: “And these things I write to you in order that you may be very well off (happy).”
• Eastern Highland Otomi: This here I am writing to you so that we (inclusive) all will have very much joy.”
• Tzotzil: “Therefore thus I write to you (pl.) this in order that thus most happy we (inclusive) all will be.” (Source for this and two above: John Beekman in Notes on Translation 12, November 1964, p. 1ff.)