Concatenate rotations and split

[Peque]

With CadQuery, I can concatenate workplane rotations like so:

Workplane('XY').transformed(
        rotate=(0, 0, 20)
    ).transformed(
        rotate=(45, 0, 0)
    ).box(1, 1, 1)

Which works as expected, creating a cube that is rotated in two axes:

Now, I would like to:

• Start with a cube
• Select one of its vertices
• Create a workplane at that vertex and apply concatenated rotations
• Split the cube with that plane and get the lower part only

I would expect the splitting plane to be rotated in two axes, but it seems it is not:

vector = Vector(1, 1)
box = Workplane('XY').box(1, 1, 1)
box.faces(">Z").vertices(DirectionMinMaxSelector(vector, True)).first().\
    workplane().transformed(
        rotate=(0, 0, 20)
    ).transformed(
        rotate=(45, 0, 0)
    ).split(keepBottom=True)

Am I missing something or doing something wrong?