The hella lamp motor fitting is the one you pointed out. The motor plugs in there and tilts the lamp up and down by way of a twisting adjuster. It works a similar method for most adjusters.
Have you ever tried adjusting Hella twins?
The have a very fine thread, they take a while.
They are also stiff.
Most headlight adjusters including the MK3 have ones that push in and out, not twist.
If I'm wrong, I'll admit to it, if so, pictures?