Not properly dealing with it has allowed for the demons to linger and cause all the problems you see in Europe today.
Anti-Semitism never went away in Europe. It’s not just a “Muslim” problem. And even the radical Muslims of today were heavily influenced by things like anti-Semitic, anti-Zionist campaigns of disinformation spread by the likes of the Soviet Union trying to win favor and influence in the Middle East, sell weapons to anti-Israel regimes, etc...
And in general, the horror and traumas of the 20th Century from the Armenian Genocide to the Ukrainian famine have not been properly confronted, repented of, and healed...
One hardly knows what repentance and healing means. The Germans payed all kinds of reparations. To this day they blame themselves in a way that the russsians never did nor the chinese or the cambodians. their self condemnation is so great that they’re even willing to will themselves away as a people. its sad.