IOTL, there was an enormous, pervasive Greco-Roman (especially Roman) influence on liberals in the late-18th century. This is most obvious in the French Revolution (look at Napoleon's iconography, or all the Classical paintings they loooved, or so on and so forth), but it showed up in the American revolution and elsewhere as well. How could you change this so that people look more to their own ethnic traditions to describe and define their liberal movements? Eg., English and American liberals thinking of commonwealths, not republics, or Germans thinking of the free cities of the HRE or the Swiss or such. Perhaps an earlier Romantic movement? An earlier development of nationalism?