Sadly that (low aggression) helps me only a tiny bit, although i do not play Death and Taxes, but my own thing instead. (and although low aggression somewhat decreases craziness, it also makes AI too passive when it shouldnt be like that)
For example in my current game:
Here you can see England owning random provinces in Sicily, Rhodes, Cyprus and Trebizond of all places.
Here you can see England owning random provinces in Norway and Sweden.
And here you can see the sorry state of England on its island. You might think that its not so bad, but id like to point out that from 1399. until the date this screenshot was taken, England has had (core giving) missions to conquer every single province on the islands. Those few missions that it did complete was actually due to randomness of cascading alliances, for example it had a mission on Irish minor that was allied with France when French dowed England, so it gobbled it up. Meanwhile, England managed to completely fail to conquer Scotland (has had this mission from day 1 i think) and right now as you can see parts of Scotland are owned by Castille, which England completely ignores.
My problem with cascading alliances is that AI is unable to make the difference between random wars and wars it starts with a goal. It spends too much resources conquering retarded stuff that it should never go for (or almost never) while it completely ignores stuff it should conquer. In order to maintain those random provinces in the Med. sea, England needs to send its fleet there all the time, and keep lots of units close by, and same goes for Scandinavia. Meanwhile, France, or Castille for example, are able to use their inferior fleets and simply land in England because ENG is too busy trying to maintain 25 different things, so in the end it will lose every one of those provinces, while achieving 0 of its national goals.
You can see very similar things for other countries as well in that Screenie. For example, via cascading alliances Naples has got crapload of random provinces (for BB) all around Ottomans, provinces that its obviously about to lose, because there is no way it can defend them, as you can see. Same goes for Morocco (!!!) that conquered Candar, Crete and half of Cyprus, not to mention held whole BOSNIA and half of SERBIA at one point. Or ottomans, who as you can see spend their resources fighting Bohemia and Austria (for the last 100 years), while they managed to take Thrace (Constantinople) only 25 years ago from Corsica! (they just ignored Thrace for over 200 years despite it being just there for the conquering, its owner unable to put up any resistance).
I do understand that this is a mod, not the vanilla EU3, and that would be a valid argument. However, the very same things that plague my MPM games happen in Vanilla as well, and furthermore, if AI worked well in vanilla, it would work well in mods as well (in theory) since no mod is able to actually mod the AI behavior, just the resources it has at its disposal (and i assure you both Ottomans and England have much more favorable strategic resources in MPM compared to vanilla).