If you have ever done programming before you know that one tincy wincy fix will break an entire project. It may take time but these things are worth the wait.
While this might be true, the amount of breakage that happens can be mitigated by handling how systems are coupled together.
Based off the nature of all the bugs I see it's pretty likely that the AI is not connected to the same rules system as the players at all, and instead tries to mimic all the rules the player has in a way that makes sense to the AI code.
This probably means every time something changes that is part of the players rules, the same change has to be made to the AI rules in such a way that makes the net outcome exactly the same. If so, this must be maddeningly difficult to manage.
Speculation, but it would explain the odd issues that just make it seem like the AI is playing a completely different game than the player. In a very real sense they probably are, in spite of the best of intentions.