Actually, you should not have to worry about the orientation of the faces if you set up the setup as follows:

[![enter image description here][1]][1]

Instead of changing the points of the geometry here, I change the whole instance instead, which basically preserves the normals.

However, to accurately answer your question regarding the normals of the faces, it would be helpful if you share your blend file.

[<img src="https://blend-exchange.com/embedImage.png?bid=yzrj234W" />](https://blend-exchange.com/b/yzrj234W/)<br><sub>*(Blender 3.2+)*</sub>


  [1]: https://i.sstatic.net/FOoqG.jpg