Decided to test AE between what the AI gets and what I get. To do it, I simply started up a game in observer, waited for a war that looked like an interesting test subject and when it peaced out I went to the monthly autosave before it, set myself as the winning country and took the same peace deal. Seemed easy enough.
Here's the 4 saves pre-peace deals:
https://dl.dropboxusercontent.com/u/46623133/eu4/AE test games.zip
Results (feel free to try these yourself with the saves in the above link):
1) Mamluks (not lucky) full annexation of Ramazan. AE was the exact same for the AI and myself.
2) Muscovy partial annexation of Kazan (including returning Perm to Perm). AE was roughly 25% less for the AI. A few countries were a point off, but I assume that to be rounding.
3) Burgundy annexation of Barrois from Provence. AE was the same for the AI and myself.
4) France annexation of 3 provinces from Burgundy. AI got roughly 25% less AE than I did. Similar to Muscovy a few countries were a point off (one was 2) which I assume was rounding.
I also watched one where Poland took a large chunk of the Teutons getting over 40 AE with several countries. I came up with the idea to let the game run another 6 months and see what happens to compare if as the player I would get a larger coalition than the AI. In both cases only the Teutons joined, and in the process I forgot to get the pre-peace save.
I hope to find some more time later to let it run a bit longer and see if I can catch some scenarios that aren't quite so straightforward to see how they add up.