idk--I'm not that smart (maybe Heavenfall knows?). I've never seen a negative balance of gildar--let alone one of that amount. It was my understanding--according to the manual--that troops would revolt or go on strike if they didn't get paid. Sounds like a glitch...1.1 is right around the corner anyway
How to tell when you're playing a game too much; someone randomly references your name on the forums (as a source of knowledge), and you see it and reply within the hour.
For players, you'll start losing units after 20 turns without being able to pay them. But for a player, it would be impossible to go from -8000 to -14000 without mods. I'm guessing the AI just isn't fiscally responsible. It's also possible that he somehow created a unit that was worth a loooooooot of gildar. The wages for that unit would be huge.