weird plane-to-plane alignment behavior

I am trying to port the Font Parser component from VB.net to C# (as a personal exercise and also to add some extra features as text justification and other stuff), but I stumbled into a weird plane-to-plane alignment behavior that I don't understand.

The original font parser in VB.net performs a plane-to-plane orientation of the strokes to go from the WorldXY plane to the assigned input plane (and it works).

When I translated it into C# the strokes are scattered away and do not align properly.

If I output the stroke and perform the alignment in a separate component (standard or custom C#), the alignment happens correctly.

Any idea why plane-to-plane alignment acts funny inside the C# main component?

Screenshot here (and the GH definition attached):