How do you know that your assertion is correct? Are you assuming instead of proving your assertion to be true?
Does the New Testament directly say whether any of the apostles or NT prophets directly did any translating themselves in the NT words that proceeded from the mouth of God by inspiration to them?
It could be that the Holy Spirit of God actually did any translating of Old Testament passages in Hebrew or of any statements first stated in another language as He gave them the NT words to speak or write by the miracle of inspiration of God. When a verse gives both an original language word and the translation of it, the Holy Spirit of God could be the one giving both to the human author so that he received the words to write without having to do any translating. If the words of the New Testament proceeded directly from the mouth of God to the apostles and NT prophets, why would they need to do any translating in writing the words given to them by inspiration of God?