Their failure to use NBC in 1795 is indicative of nothing, except perhaps that they just didn't think it was all that important. After all, it was already safely in the Constitution, and if that Austrian prince Ferdinand Maximilian had tried to run for President (instead of Emperor of Mexico), well, it just wouldn't have been legal!
Even if Congress had meant to redefine the meaning of NBC in 1795, they lacked the power. They would have needed two thirds of their members and three quarters of the states.
Congress certainly has the power to change Acts of Congress. It could very well have been that they revised the Act of 1790 because the description they had placed in it did not match what their original intent was and wanted to remove/correct their mistake. They may have come to the conclusion that Congress did not have the authority to re-define the term natural born citizen without an amendment process and thus removed it from the Act.
My point is that you cannot look at just the 1790 Act for guidance on this issue. Both Acts and the change made in reference to the term natural born citizen to just citizen together tell us something very important.