The reason it can't play Pythium is due to the gladiators. It recruits 800g worth of units that can only be used in a single fight.
I think if you disabled them Pythium would play a lot better.
I think the AI is good at both fire and death spells. They can skelly spam, and shadow blast, plus use generic fire evocations. They're also decent at air magic. Possibly a nation of N1D1?2 and N1F1?2 mages with ANDF as the random picks, plus low gold mid-resource units that are very tough for their cost (like Alae Legionnaires perhaps).
More importantly, the AI needs to NOT have a lot of things. No gladiators, no horn blowers or standard bearers, no 120 leadership useless commanders that cost a lot, etc. Ideally they'd have a mix of all useful troops where the only difference is a high damage 2-hander, a high damage 1-hander with a shield, or a mid-range 1-hander with a shield. Lots of survival types would help, but a high enough resource cost should prevent the AI from putting 500 of them in the same army and starving to death.
A human player playing the nation would be very powerful with the Air/Fire combo, but the lack of astral would be a big offset. That's just where my line of thinking took me, maybe you have a different idea.