Exegesis:

tote diēnoixen autōn ton noun ‘then he opened their minds,’ cf. on v. 31.

nous ‘mind,’ i.e. seat of the intellectual capacities.

tou sunienai tas graphas ‘to understand the scriptures,’ either final, ‘in order to…,’ or consecutive, ‘so as to…,’ preferably the latter.

Translation:

He opened their minds to understand, or with another metaphor, ‘he enlightened their mind (or, clarified their thoughts) that they could understand’ (Balinese, Shona 1966); or again non-metaphorically, ‘he made them able to understand,’ ‘he caused them to know well’ (Tzeltal); and see on v. 31. For to understand cf. on 2.47.

The scriptures, or, ‘the meaning/contents of the Holy Book’ (Balinese), ‘what God’s book says’ (Tzeltal).

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.