I made a grid-based coordinate system. I printed out the grid numbers to make sure I was building it correctly.
There was some horizontal misalignment. I also resorted to printing out debug spheres as well, and the spheres ended up in the correct locations. It seems that draw debug text does not center the text around the location. There will be some horizontal misalignment.
The pictures should make it pretty clear.
I would suggest that the text would also be centered around the specified location when using the node / c++.