What line(s) did you mod to make it 75%?
I didn't mod the files directly, I just manually set Germany to "Restore the Kaiser" in the game options tab for most of the games I play, along with "always free" wargoals (for when I want to conquer the world, but don't want to go fascist to do it).
I'd heartily agree with you if the AI could actually manage civil wars of majors in a satisfying way and they didn't turn into a grindfest.
Currently if you see a major doing a civil war you can safely assume it out of the decisive part of the game as by the time either of the sides can grind to victory the rest of the majors has basically finished the match.
Really? Is this a common occurrence in the most recent versions of the game? Because in 1.8x UK almost never has a civil war, and when it does have one it's over with very quickly. The last time I saw the UK have a civil war, I was South Africa. The UK called me into the war immediately (WT was crazy high because Japan had to manually justify on China) so I sent my army to Britain to help kick Oswald Moseley in the junk.
The war ended before my divisions arrived. It was over and done with in less than a month. And that's pretty typical of a UK civil war, from my experience. The rare French civil wars play out similarly.
The only civil wars I see that take several years to play out are the South Africa Communist civil wars. The terrain is terrible and both sides have garbage divisions and no way to equip them. That civil war usually devolves into the two sides staring at each other waiting for WT to get high enough for the UK to join and end it.