OTL, the Treaty of Versailles and the construction of Post-WW1 Europe was a complicated affair. Germany was the only Central Power to survive as a major player on european politics, but felt it was betrayed and treated unjustly, despite not actually losing that much land or power. Italy didn't see the gains it was promised returned, and various other issues. Now, I don't think you can prevent the revanchism that gripped Germany without it winning the war, so I'll admit hindsight went into how i treated the German Empire- probably bad form, but I think Germany got off fairly lightly otl.
A summation of the changes to otl
- France and Belgium each got expansions on their eastern borders, but Germany still has substantial power in the Rhine.
- Poland gained some Silesian land in order to strengthen an industrial base
- Italy got her adriatic claims, at the cost of Yugoslavia
- Hungary kept more of its prewar land.
- Greece gets Instanbul and more of Thrace,