Others have answered to the other part of your question. To the first part, the Canon Law prior to the current one (the former having now been abrogated by the later), did mention that separation in this way was “desirable”, as fitting with ancient customs. But the language did not make it mandatory, and I do not know anyone who ever sat separately at Mass in this way. (Keep in mind that the Catholic Church is not just an American thing…so some customs that seem strange to us may have been quite normal elsewhere.)
Here is what that 1917 Canon said"
§1. It is desirable that, consistent with ancient discipline, women be separated from men in church.
§2. Men, in a church or outside a church, while they are assisting at sacred rites, shall be bare-headed, unless the approved mores of the people or peculiar circumstances of things determine otherwise; women, however, shall have a covered head and be modestly dressed, especially when they approach the table of the Lord."
Neither of those parts of the now-abrogated Canon Law are mentioned in the new Canon of 1983.