I am reimplementing the logic in the upstream STL writer in pythonocc-core in order to obtain a surface mesh without having to resort to File I/O, and it seems that calling BRep_Tool.Triangulation should update the TopLoc_Location it is passed, but, at least according to its DumpJSON method, this is not happening. Here's the core of my traversal loop:

    exp = TopExp_Explorer(shape, TopAbs_FACE)
    while exp.More():
        face = exp.Current()
        if face.Orientation() == TopAbs_REVERSED:
            print("FIXME Reversed face")

        loc = TopLoc_Location()
        tri = BRep_Tool.Triangulation(face, loc)
        if tri:
            trsf = loc.Transformation()
            for i in range(tri.NbNodes()):
                p = tri.Node(1+i)
                p.Transform(trsf)
                nodes.append([p.X(), p.Y(), p.Z()])

A full self-contained example is also available.

In the full example, I am trying to mesh a box. STL export (ostensibly using the OCCT C++ code above) works fine, but with my reimplementation, I get a mesh that looks like this:

I.e. all faces of the box seem to coincide in one plane, seemingly consistent with lack of transformation information.