Verse 5 explains that Nephi delights in Isaiah because he came from Jerusalem and he understands the things of the Jews. This is not a clear declaration that he was trained to understand such things, but scribal training provides a logical backdrop to the reason that Nephi might suggest that he understands these things of the Jews. Certainly, his use of Isaiah has previously suggested that his brothers did not fully understand those particular things of the Jews.
Verse 6 tells us that Nephi did not teach his children after the manner of the Jews. Even though this is in the context of teaching religious teachings, it is an important aspect of our modern expectations for what we might see of the Old World in the Book of Mormon. Critics of the Book of Mormon might suggest that we ought to see elements of the Old World in the New World material culture, but Nephi clearly states that this might not be the case. If Nephi intentionally doesn’t inform the second generation of the things of the Jews, there is little likelihood that such cultural influences ought to be seen in the New World.