Oh okay so we're just waiting for a fix then?
It's literally the hideouts being way out of control, so if there's a hideout, a certain type of bandit will control the region. I have seen a mix of different types due to hideouts being relatively close. Charas/Jaculan have a Sea Raider and Mountain Bandit hideout relatively close to one another so you'll be able to see a mix of them if they both spawn.
I sent an email with the save to the provided address. I used cheats due to being unable to play the game normally as the bandits got out of control in '84. I lost men faster than they replenished in villages and towns, villagers were getting caught and slaughtered, so towns start starving and caravans get destroyed before they make any real returns.