The only two things I'm really hoping to see in the patch is the SOV not leaving the Berlin-Moscow Axis, and an ability for a faction leader to kick out a member. When Spain takes Turkey and India, and puppets Ireland and Switzerland, it gets a little annoying. Speaking of that, a better peace conference system would be nice too.
I agree that a better peace conference system is needed. It is also not merely that the current intention is flawed, but there are serious bugs that have results from multiple wars crossing over into the conference even though some of those wars have not ended (and they were never merged).
An example would be an MP game where I allowed Finland into the Axis when the Soviets invaded them in '39. I only did this because in a previous game I had passed that and they were accepted into the Allies with an even more flawed peace conference after.
If the example of Finland joining the Axis, my opponent and I had house rules prohibiting an early war between Germany and USSR. So we considered this a sham war. Neither of us fought the other (except for Finland of course and as Germany I did not join that war). Hungary, however did join the war. The Russians did not attack Hungary per our agreement and the Hungarians only lost around 10k soldiers in their border skirmishes with the Russians.
Now comes the Peace conference in which for some reason the UK was at the table presumably because they had a war with Hungary (though the two wars did not merge). I, the German player was not at the peace table. Hungary was forced out of the Axis and became a democratic state.
With the current peace system letting Finland join either faction totally breaks any attempt at a historical game. If either UK or Germany is AI controlled, Finland will join one faction or the other every time.