The Septuagint (the Old Testament) was also in Greek, and translated around 200 BC, and was the official scriptures read in synagogues at the time. If they read scriptures in another local language in the synagogue, they were also required to read it from the Septuagint in Greek afterwards because that was the official language for scriptures in the synagogues. Only after Romans started persecuting the Christians did Jews start separating themselves and trying to put together a separate canon and translating it back into Hebrew, which wasn't accomplished until the 1400s.