That wiki is out of date or flat-out wrong. I was well into the green when I got hit with the EP. I was playing the Papal States and fighting Venice and their little clutch of allies with the Ottos swarming up the Adriatic. I had Treviso, Ravenna and Friuli occupied and Brescia and Padovia underway. There was no way I was losing by -25 when France intervened.
As
@Republic of Mercury says, the tooltip means you can enforce on anyone with
better than -25% Warscore. If you had been losing by 25% or more, they couldn't enforce peace on you.
As for the territory taken: The AI offers the peace deals it wants for the war to end. They don't "get to take" anything under 10% - firstly because it's disallowed, you can only suggest white peace when at less than 10%, second because you can just tell them to stuff it. The only situation in which the AI can take what it wants is when it has you 100%, in which situation they can take up to 100% warscore without you getting a say. You can do the same to the AI. How much warscore a province costs is governed by the CB used, Diplomatic ideas, Admin Efficiency and some Great Works. In the late-game, you can stack this to take truly staggering amounts of land. I'm fairly sure I've seen a player annex all of Ming in one war, without Reconquest (which is the best CB for landgrabs, but usually requires you to have lost that land in the first place).
When it comes to Enforce Peace, check which AI powers have interests in the same region, and try to befriend the ones more powerful than you. The AI is very unlikely to intervene against you if you can get a royal marriage, an alliance, or even just get relations to Friendly. Sometimes, this just can't be done, and in that case, check the targets you're declaring wars on, and bring your own allies when declaring on them. If you can use overwhelming force (France is a good example for the Pope). The AI likes to use enforce when their joining would swing the pendulum massively against you, so if you can stack the odds significantly in your favour, to the point where a big neighbour friendly to your target would only make it a level playing field, then you're usually good.