Exegesis:

idontes ‘having seen,’ the object has to be supplied from the preceding clause and is either Mary, Joseph and the child, cf. “them” (Williams), or the child only, cf. “him” (New English Bible), “it” (Revised Standard Version), preferably the former.

egnōrisan peri tou rēmatos tou lalēthentos autois peri tou paidiou toutou lit. ‘they made known about the word that had been spoken to them about this child’; peri tou rēmatos has the function of a direct object in the accusative with egnōrisan (cf. v. 15); when connected with a form of the verb laleō ‘to speak’ rēma means ‘word,’ not ‘thing,’ but here it refers rather to the content of the word than the word itself: hence many translators render tou rēmatos tou lalēthentos autois as “what had been told them” (Translator’s New Testament) or a similar translation. egnōrisan has no indirect object, which is supplied variously: (a) “them”, i.e. Mary and Joseph (Williams); this seems the natural supplement when the omission of the indirect object is not intentional; (b) “everybody” (Phillips), this is in accordance with the following verse which presupposes that the story has been spread. In the order of the story it is only logical to think of Joseph and Mary as the first persons to receive the message of the shepherds, but Luke has already in mind what follows, i.e. the reaction of all who heard that message, and in order to prepare the reader for what follows he does not mention the indirect object of egnōrisan ‘they made known.’ According to this interpretation Luke’s omission of the indirect object is intentional.

paidion ‘little child,’ cf. on 1.59. The term brephos ‘babe’ (vv. 12, 16), paidion (here, v. 27 and v. 40) and pais ‘boy’ (v. 43) apparently are used to suggest phases of Jesus’ growth, the end of which is indicated by the use of ‘Jesus’ without a qualifying apposition (v. 52). But this is not to be pressed, as is shown by the facts that brephos can also mean ‘embryo’ (1.41, 44), and that paidion here has the same referent as brephos (v. 12), although its general range of meaning is wider, covering the whole period of childhood.

Translation:

When they saw it, or ‘them,’ as preferred in Exegesis.

They made known, the same verb as in v. 15, probably in order to suggest that God’s message brought by the angels now finds its parallel in the message brought by the shepherds. New English Bible has “made known” in v. 15, but here “recounted”, another way to refer the reader to the first message; similarly Toraja-Sa’dan, ‘go-along-the-whole-length,’ i.e. tell again, keeping exactly to the original message. Some translators, taking the indirect object here to be ‘everybody’ (as preferred in Exegesis) have chosen a somewhat more encompassing expression, ‘to tell all’ (Tboli), ‘to make-widely-known’ (Bahasa Indonesia), ‘to make known everywhere’ (Ekari).

The saying which had been told them, or, ‘what the angels had told them.’ Tboli renders ‘that which they had heard,’ probably to avoid repetition of ‘to tell.’

Child, cf. on 1.7. The series “babe”–“child”–“boy” will require careful handling in receptor languages that have a different division and/or a different number of grades, or no grading at all, as in Tae.’ In some other cases a grading term, though existing, is unacceptable in this context for various reasons, stylistic, as in Dutch (where the usual term for the first grade, a borrowing from English “baby”, would sound ridiculous), or honorific, as in Balinese (which, though possessing a word for “babe”, cannot use it when referring to a child of high rank), or semantic, as in Bahasa Indonesia (where the term ‘boy’ came to be primarily associated with the concept ‘servant’).

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.