What I would imagine is that the Syndicalism of Marx, Engels, and Proudhon (the Great Radicals) would have a profound effect on the way that the politics of these countries evolve. I would say that the biggest effects would be seen in the more industrialized areas of Europe: Germany, France, the Low Countries, Northern Italy, and Great Britain. With more of a focus on the organs of revolution, and with a scenario where you don't have Great Power sponsorship of nationalism, then I think that the nationalists will be pushed into more radical arenas, arenas where the revolutionary ideas laid out in the "Freeman's Manifesto" (I don't think the "Syndicalist Manifesto" has the same ring, maybe im too much of an OTL Marxist . . .) our alternate statement produced by the Great Radicals, would find fertile ground. In the more divided politics of this alt-Europe the radical labor unions, student groups, and nihilist terrorists . . . sorry I mean self-less freedom fighters, my bad . . . cross the boundaries of princely states, linking together based on language, not borders. I think some kind of crisis in Germany, precipitating a National Strike, would start the "second '48," and spread into Italy and France. The organized labor movement and fellow travelers in the student movements provide the leadership for these nationalist revolts, and find much support among the younger military leadership of various princely armed forces.
Oh, I've got the crisis. A strike in Vienna results in the arrest and show trails of several prominent Austro-German syndicalists. Their trail creates massive amounts of rioting, and the powers that be decide to have a public hanging to show that they mean business. Their execution never happens. While they are being driven to the gallows "Freeman's Brigades," the popular name for syndicalist terrorists, ambush the guard and set off a revolt in Vienna. Street fighting rages for a few days, then the syndicalists declare victory. Elsewhere in Germany, the fighting in Vienna spawns other political violence and soon several major German cities are under "the People's Control." Chaos in Austria provokes Hungarian and Italian revolts. In Italy Garibaldi appears in Milan, then Venice, then leads an army to Rome, while the Sardinia-Piedmont troops battle with pro-Garibaldi rebels. In France the Communards, the popular name for the Syndicalist sympathizers in Paris, take to the streets and declare the "People's Republic."
In Germany and Italy the organizing done by labor unions was essential for these revolts united leadership. The unions and student organizations working together are able to establish governments, and their ties into the the armed forces of their respective armed forces bring about mutinies, the killing of officers, and in many places in Germany, coups in the name of the Volk.