All the painting magic happens in this main routine. Then each component may or may not be drawn in its own class by calling the subroutines. This can be found in the OpenGL.Designer.cs
You are correct. The image in GE may or may not line up with the GPS coords. If you scroll though the years it can be off by as much as 30m. A good test is to draw your boundary in GE, import to AOG, then go try to stand in that location. If you flag something you can see in GE, you can export the flag and see it that way as well. It is spot on dead accurate in GE to simulator and back to GE. But real world it needs corrected and possibly corrected each time GE updates its photos.