Update: Just saw https://forum.snapmaker.com/t/what-file-format-for-luban-laser/10230/10 which discusses exactly the same problem with wrong-sized imported objects.
One other thing I forgot to mention about the DXF/SVG import: regardless of the orientation in OpenSCAD, the primary axis is aways the Y axis when importing into Luban. This means that regardless of whether the scale is created along the X, Y, or Z axis in OpenSCAD, Luban imports it with the scale running along the Y axis, requiring a rotation. Not a big deal, but unexpected and yet another thing to deal with when resizing and positioning. Will attempt a luban upgrade to see what’s up, as this appears to be fixed: https://github.com/Snapmaker/Luban/issues/943