Well, why do you think this is Anglo-centered Chauvinism? Slovaks naturally perceive Jánošík as Slovak national hero.
I would not compare Jánošík to Robin Hood. In reality Jánošík was not such hero, he was a bandit and robbed anybody regardless of social status. But OK, people made of him a hero who robbed Hungarian aristocrats. It reminds me blind voters who love their leader (a head of a political party) because he raised the tax for banks, but at the same time he robs poor people in other ways (like e.g. paying for everything they need to do in bureaucratic system). It is clear that he was a Slovak born near of Terchová, a Slovak town, then in Austria-Hungary and mostly lived in this region .. whether he is also a Polish hero or not, I don't care. After all, why not if he went to rob behind the borders of Hungarian kingdom? In this case he may be a hero for Moravians and Silesians too, 'cause he robbed there as well. But I don't think it's something amazing, he did it for own profit. That's why he wasn't like Robin Hood. People love the legendary Jánošík, not the real Jánošík.