Thank you for the examples, they are quite nice! Because I simulate the angles and sizes of shadows to cycles of the Sun(s) and planets, I used the first example because I like the manual control of it.
DrawingCanvas is way more efficient and less time consuming for this than the method I use. But, I have encountered an issue; it works nice with "Fullscreen mode: off", but since I have layouts up to 1M x 1M, I use scale outer, and this seems to break it - the shadows are in the wrong positions (at an offset).
Weirdly, what fixes it is zooming out the layout in my case 24% (I have those controls built in) so after that zoom out and further they are in the right positions. Do you know what might cause the wrong positions on scale out mode? I might be doing something wrong too while adjusting it for large layouts.
Edit (updated your c3p file to show issue):
drive.google.com/file/d/1yNc1nvCW7_xbjtRdvEowmikwrJYRRMRJ/view