These are all great points, and of course, I didn't mean to trivialize any of them. I can't say a federal state
would actually work for the EU, precisely because of these issues.
>Imagine a president who doesn't even speak the native language of the vast majority of people in the country.
This actually reminds me of Spain. Their leaders, while they speak the native language of a majority, it's not a vast majority, with very significant minority-language areas (Catalan, Basque, Galician). And that country sometimes seems to be barely holding itself together, with Catalonia attempting an independence referendum a few years ago that didn't end well.
However, this is a quibble, but as an American I'd argue that if the EU did federalize, they shouldn't have a president at all. The US has a presidential system and it kinda sucks (see: frequent government shutdowns). I think a parliamentary system works better in practice, or perhaps something resembling Germany's system (since Germany also has a federal government).
>So the squabbling mess of European powers, barely coordinating under a balance of power system at home, was dramatically successful militarily and economically (at an even more dramatic human cost)
I really don't think those days are coming back. Europe was so successful back then because it was far more developed technologically. That advantage is long gone now. Plus, Europe's population just isn't what it was. And I'm not a historian, but I thought the reason China didn't develop as fast was all self-inflicted: they intentionally turned inwards and refused outside contact.
Anyway, perhaps you're right and the current state of the EU is the best they can do with their circumstances. Still, I suspect it's not enough: I don't see this as a stable system. They can't even keep one or two of their own member states from torpedoing all progress, and if the US weren't there to defend them from Russia, they appear to be powerless there too.