...so in the end it would be simpler to just disable creating nations.If you however think Hanover and Sweden both are in the same situation as Italy, then add their tags to the End-game tags.
Take Prussia.
Prussia isn't end-game tag, and it shouldn't be. To be Prussia you need to be Pomeranian, Saxon or Prussian, have Prussia (Königsberg, Warmia and Danzig), be Protestant or Reformed. To create Mughals by Prussia you'll need to shift your culture like Italy need. Do you believe Prussia should be able to create Mughals, and Italy shouldn't? Is Italy more magical title then Prussia?
UPD:
To create Hanover you'll need to be Westfallen; should they be added into End-game tags?
What about Netherlands, required to be Dutch?
Or about Greece, need to be Greek?
Or Ireland, required to be Irish, who need to change primary culture to create Great Britain, by the way?