A common problem with spline curves is users try to use wayyyy too many points. More points is not equal to smoother curve.
Try an experiment. Start a new sketch over your NACA sketch. Sketch a two point spline endpoints projected from your NACA sketch. Spline is straight line. Now, edit the handles to try to match your NACA along one side. Insert node where you think you need one for more control and try adjusting all three handles (you can add dimensions) to match the NACA. Repeat if necessary. My guess is that with surprisingly few points you can match the NACA well within actual possible manufacturing tolerance. (is this going to be layed up fiberglass)
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