Eleutheroi armies spawned by script in non-eleutheroi territory are very passive, regardless of odds or difficulty level. Their behavior is very different from that of normally occurring rebels or brigands or even eleutheroi armies spawned by script on eleutheroi-held territory.

That makes spawning eleutheroi armies by script useless for simulating a civil war, because the eleutheroi would have to be placed in player-held regions.
Sorry but I still beg to differ . Another clear example is the "Caledonian Invasion": regardless of the circumstances, Camulosadae will always be attacked by a scripted Eleutheroi army in the early Casse game. Non-scripted Eleutheroi bands still attack me at favourable odds for them and act aggressively if i play on Hard, so there is nothing conclusive for now because our experiences are very different .

Anyhow, if the problem is still specifically about spawning scripted guys on non-eleutheroi lands, an easy workaround would be to spawn them on eleutheroi territory then move them to Roman lands. My two cents.