I tried playing around with RayBounce but I am afraid I overcomplicated the problem:
What I did was open the Architectural file containing the ceilings (I know you have many…), I loaded my Electrical File, I ran RayBounce inverting the points and the category, I then sorted everythign out to obtain an excel file with the Light Fixtures ID’s and the level and offset they should be at.
I did not continue testing this method because as you can see it is time consuming, but ideally you could do another simple script that reads the excel (this time in the file in which you wish to move or place objects) and assigns the correct level and offset to each component.
I know this is not an answer and that you wish to directly place elements while I want to move them, but you could easily change the green group with the import coordinates from your dwg extracted coordinates.
I’ll try to play around with the the Solid.ProjectInputOnto node and the python scripts, both of which however did not work on the first try.