It’s probably more work then you were looking to do, and these might not be completely historical. But here are some thoughts or suggestions that you might have already thought of and maybe some new ones.
1. What if you made a land route between Russia and Sweden and then made it possible to cross between Denmark and Sweden as well? That’d up the competition for Sweden so UK couldn’t just waltz in and then forever secure it with their navy. Maybe just a callout box or dotted lines or some such. Or arrows and text with ‘to such and such terr’ like that one WWI game I can’t remember the name of.
2. Possibly adding more fleet for Russia & Austria-Prussia in the Baltic.
2. Could you just remove the VCs in question?
3. How about making all of Spain but Gibraltar and all of Sweden true neutrals and impossible to move into? You might have to recode the straits bit for Denmark or just include those terr in the game. Otherwise just make them completely game neutral.
4. Stretch the Ottoman presence further west, maybe give them an outpost in Tunisia or Tripoli with some fleet units, general/camp, plus some forts/ground pounders. Let them contend with UK/France for Spain. Maybe do this in conjunction with #1 or #2.
5. Up the Victory conditions for UK/France to account for the ease of getting those VCs.
6. I’m running out of valid thoughts.
7. Seriously stop reading I’m out of ideas.
8. Why can’t we have a A&A Global FFA?
9. Add a VC in Baghdad and/or Jerusalem? And then expand Russia closer to it so they can contest it with Ottomans?
10. Nuke Ottomans or Austria-Prussia as well and make it four player. Those VCs would be easier for whichever country made the cut + Russia to grab. Up ALL victory conditions to reflect that more VCs are up for grabs.