https://www.libertarianism.org/columns/federalism-proudhon-ostrom
And still considered himself an anarchist (from above link):
"In The Principle of Federation, Proudhon settles upon referring to himself as a federalist, though without completely abandoning anarchy, defined as “the government of each by himself” or “self-government.”
So, I'm still not sure that he couldn't decide between anarchy and socialism.