Christian writes about the nightmare of using the proper name for people in an international context. I’ll add that even in the same country/culture, you can have a hard time, because of another factor: the generational context.
People don’t necessarily address other people from their generation the same way as they would address people from different generations. And these “rules” may also vary when people age. Even people from the same generation can have different ways to address people.
All in all, naming someone is complicated everywhere, though it is more complicated in international context.
I’ll also add that there are at least two persons involved in a conversation, and that while it is nice that the sender tries to make an effort to address a person the proper way, the recipient should also not take it bad when someone from far away uses the wrong name, and don’t make a fuss about it. That’s called tolerance.
To give an example that is not about names, but about such tolerance, President Obama recently made a visit to the Japanese Emperor, and bowed before him. If you are living in the US, you probably heard about that, because the media there made a fuss about the US president bowing. It so appears that by japanese standards, he indeed did bow too deeply. But the japanese didn’t care much. He’s not japanese, he doesn’t have the cultural background, and therefore can be wrong. At least he tried. What actually made news in Japan is the US news making a fuss about it.