I think having Aberration as a base is good so that there is no need to reinvent the wheel.
Some ideas:
1) Brittany, Scotland and Eire all had colonial empires, mostly in the Americas. Then late 18th / turn of 19th, there were independency wars and several large new countries formed of these celtic colonial possessions. Now as the three celtic states are again having only their european possessions, they have seeked strength in numbers by allying each other, as in the growing nationalism they see each other as more like brothers than french, germans or iberians. Then after 1836 they either grow stronger on their own or one of the three gains a leading position and unites the rest under his banner as a Celtic Federation.
2) Union of Kalmar has gained Norway from weakening Scotland and has proclaimed itself as Scandinavia, uniting swedes, norwegians and danes under common banner. But their lands are sparsely populated and they have lost their colonial possessions to freedom movements as well.
3) Granada is still a large empire stretching from northern Iberia to deep into West Africa and into North Africa up to Tunisia or Tripolitania. All is not well in their empire however, as the ideas of nationalism are flooding into the empire and various minorities like iberian christian groups, berber groups and west african tribes are now calling for recognition of their own cultural identity.
4) Kaliphate has incorporated Egypt, Mid-East, Arabian Peninsula and eastern Persia, but as more and more power goes into the hands of religious leaders, the new ideas of industrialization, democracy and capitalism are making little headway into this bulwark of traditionalism.
5) Byzantium faced a revolution and turned into a democracy. While turks and bulgars are accepted as equals of greeks, the position of the republic is a difficult one between Kaliphate and Hungary, which don't agree that democracy is a good thing.
6) Hungary has adopted a reactionary stance with the lead of it's powerful monarchy among the turmoils of new age. Will the autocratic monarchy be able to answer the demands of industrialization? And while various slavic and german minorities are still quiet, the smell of unrest is in the air.
7) Central Europe has several medicorde powers that could lead their people into glory. Burgundy, Savoy, Genoa, Sicily, Tuscany, Bavaria, Cologne and North German Federation (ex-Hansa) could all rise to into great power, but may also remain forgotten. Most of them have small colonial possessions too.
Other smaller ideas:
- Ukraine has gone into Siberia
- Teutonic Order has been secularized into Courland, Baltic Union or something.
There should be some RotW majors too. India? Japan? Something in China? American new countries would have potential to majority, but they would be still growing mights, like USA in 1836, though smaller.