That has a simple reason: Germany is a larger country in a unified Europe now. After recovering from the effects of the reunification, you have now a stronger and larger economy with more and larger trading partners. For the larger export success are a few simple reasons responsible:
* the east european market directly next to Germany is now larger and easier to access. Poland.
* Germany is no 33% larger than before the reunification. Once the added economy started to recover from the effects of reunification and many investments in East Germany were done, the now larger economy, contcentrated back on the european and world market.
* globalization has nicely enhanced the reach of even small companies in rural Germany to trade with even remote locations
> It is entirely due to mistakes in macro economics
That's entirely wrong.
...which in turn strengthens the German position, right? In turn giving them de facto economic success?
Germany has not had anything like this level of current account surplus before. It is entirely due to mistakes in macro economics (wrong parity within the Euro and a refusal to boost domestic demand).
Sadly Germans seem unable to understand that their surplus is not a sign of economic success, but the result of misguided policies that keep the rest of Europe in recession.