I’m afraid I don’t know how the simulation mode is implemented. I’m not a member of the core development team, I’m just an enthusiastic contributor. I’m based in the UK and I’ve not run into any issues using the simulator, but I rarely use it. It’s a nice feature, but you can work through the tutorials without it, so long as you’ve got a microcontroller board.
In addition to the tutorial material on the XOD website, there is also a new guide for self-paced learning: Free XOD guide for rapid prototyping