I tested the spawn_character, and it half works.

I used the code to spawn a captain (not a family member) for the scipii called Asinius Aelius. The man appears, (right model for scipii etc) but he didn't have a banner. I tried adding units to his army by using console_command add_unit, but this seemed to have no effect. I could script the army to move by using move captain asinius, x, y. But the AI seemed to ignore this new character completely. So, it didn't work.

As for spawn_army, I tried editing the syntax so that it was the same as used in descr_battle.txt for historical battles (as this is what it said it should be in the CA txt files) but again, the script did not run at all (no commands were executed, before or after the spawn_army command)

Here is something weird, for some reason the line:
console_command run_ai
won't work for me. I halt the AI, but it won't start again, no commands after that line are executed. This is very very wierd as CA use this exact line in the prologue script.... WTF?