From what I understand, the AI looks at you and makes a determination if it is stronger than you, and will declare war on you. Yes, it kind of gets to "cheat" by "knowing" how many powerpoints you have in a region, and makes an estimation that it can "take you". Also, the AI aggressiveness is governed by rulevar 903. The larger this is, the more aggressive it will be. Whether there is code so that they will gang up on you, I can't say. I think not. I am generally looking at random games with two regimes. But, having a map where you have several borders with AI regimes could be challenging.
There is also the random personality, so, some AI regimes might be more aggressive.
I have found that the AI be quite timid at times. If you make a strong defensive line, the AI will actually leave you alone.
You can try to implement a diplomatic block to try and give yourself some breathing room. But, you find that the AI might think you are too tough to take on. You could also try a simple event that starts with rulevar 903 being small, and increase it each turn.
The AI has several advantages, such as free strategic movement, that give it a leg up on human players in the early going.