Beam by Curve follow-up



I wanted to post a follow up to some off behavior of the Structural Framing by curve node (previous posts here:

Im curious to see if someone has knowledge of how Revit chooses the orientation of the beam based on a line/curve. On the previous example ( Revit did not consistently placed the framing based on a curve. Most strangely, the orientation of the curve did not seem to affect the in-place orientation of the beam. However, it did restrict it to 2 options (let’s call it 90 deg vs 180 deg)

After a bit of testing (below) it seems obvious that there is some information related to the way lines and curves are created that makes its way into the structural framing placement. Yet, I can’t find a place to make that information explicit.

Any insight on this would be helpful.