Some things could made AI much more competitive to player:
1. synchronize arrival to attacked province - no one by one
2. AI should be more willing to attack with high stacks of units - now it often uses 1/3 of their stack and constantly is loosing, so I can win even having 4 times less forces + my super generals = bloody slaughter
3. AI don't look at province's unit max support, so it's often killing yourself - even sitting at home. The best example is Africa, when AI units are disappearing from attrition.
4. Why invasions are done only by one unit (sometimes two) ? England is absolutely off this game.
5. Every AI is building a huge stacks of navies and investing in naval technologies even without colonization ....
6. BB wars are good, by not made as defendless country .... AI countries should start to build huge allies blocks when facing very BB country - especially human.
7. Loans + calvary are killer in first phase of game. You can beat any AI, playing by one province nation at start. Generals should add only some percent of power to your units, ex 10-20% max - not 100% - 400% ...
8. AI is ending wars too fast. It could destroy all country, but it suddenly wants to talk about peace. Today it's dowing me, month later is asking about war ending.
9. Beaten AI should rebuild their land forces with very high prioritet - not building improvements and ships too.
10. Avaiable manpower is something fictional. Now you can waste them as you wish. This is probably the key which give ability to such fast conquest. Hoi2 system is much better.
so game need some more programming work to be better. Most options of this game are for human and they are not used properly by AI. (very slow colonization, is AI using spies at all ?, diploannexations, taking loans etc.). In my opinion option which is not used by AI, could be not possible to human.
At the end I must say that sometimes is very hard to stand vs 5 - 6 attacking enemies - so even without changes game is interesting. I had many fun from playing it.