"And the more peaceful times in Europe isn't because of democracy it's because of US hegemony"

Is it?

The US is very lightly present on the continent, as it has significantly would down its forces since the end of the Cold War. Its influence on most European affairs is mostly soft power than hard power.

If Italy and Austria wanted to duke it out over who owns South Tirol, the putative US hegemony would not prevent them from doing so, much like it didn't prevent the almost full decade of regional wars in the wake of the disintegration of Yugoslavia.

Soft power and the institutions of the west are a big part of the US power projection that prevents war. Those countries are very lightly militarized (<2% of GDP on military), and it's because they are under US protection not because they are democracies.

Yugoslavia was basically outside the US sphere or influence, and it was a regional conflict(not of vital importance) so the actions by the US were more limited. Also that's a weird example to bring up in support of Democratic peace theory as "Bosnia, Croatia, Slovenia, Serbia, Montenegro and the Serb Autonomous Regions were all formal multiparty democracies" [1]

[1]https://en.wikipedia.org/wiki/List_of_wars_between_democraci...

The EU is probably more effective at stopping Italy and Austria having a go over the Tirol. The US are quite helpful at deterring Russia from doing it's thing though.