The mechanism is roughly as follows (for MGE)
1. First check
The human player's presence of bombers (stealth bombers) and helicopters is checked. These values are added together, and then this value is compared with the AI player's total number of fighters (stealth fighters) in stock and under construction. The AI then decides which unit to build. If the human player's first value (number of flying units) is higher, then the AI passes the first check and moves on to condition 2; otherwise, a different unit is selected
2. Second check
The presence of a peace treaty between the human and AI players is checked. If there isn't one, we move on. If there is, the AI is checked for fighters (stealth fighters), both existing and under construction. If there aren't any, the check ends and the fighter construction is ignored, i.e. If the AI player is in a world with a human player, they won't start building them if they haven't built them before
There's a lot more code below, but this seems to be the main check
Here's what you can do to try increasing the number of Fighters the AI has:
1. "CA 83 C1 02 8B 85 9C FC" - find the section of code and replace 02 with a higher number, such as 10
2. Remove the link to Fighters in stock
Find "0f 84 05 00 00 00 e9 b4 fc" and replace it with "90 E9 05 00 00 00 e9 b4 fc"
I could be wrong, but overall, I think I've analyzed these checks correctly. If I'm wrong, please correct me if anyone knows anything.