In the EotE Core Rulebook on page 213 it says: "Characters (...) moving through difficult terrain must perform twice as many maneuvers to move the same distance they would in normal terrain."

Does anybody know if this only includes changing range bands or if disengaging from an opponent also costs two maneuvers in those circumstances?

I always thought of disengaging as just taking a step back to get out of arm's (or melee weapon's) reach of your opponent rather than really putting distance between yourselves, so I'd tend to say no, but I'm not sure. It would make it practically impossible for minions to get out of a melee engagement in difficult terrain, and that seems weird to me.

This may be a good question for a developer. I'm not sure if there's a RAW answer to this. I could see it costing two maneuvers or just one.

I'd say yes. The maneuver you use to go from engaged to short is "Move." I think that alone should mean that you need to make two "Move" maneuvers to leave engaged. Should your minions be experienced or expecting to be in rough terrain? Perhaps give them the talent (Swift maybe?) that ignores rough terrain.

Engaging and disengaging are part of the "move" maneuver. It does call them out as not moving very far, though.

It's also worth noting that in "The Five Range Bands" discussion a few pages later in Chapter VI, under the Engaged heading, it notes that the difference in distance between Short and Engaged is relatively minor, and taking a maneuver to engage or disengage means moving "cautiously" rather than moving a physical distance.

However, I would think that difficult terrain might make engaging or disengaging more difficult. I would say it's really up to the GM on a case-by-case basis, because some difficult terrain might only be difficult over a matter of meters, but not necessarily for moving a few feet in any direction. Like if a terrain was especially bumpy, but the bumps were like really wide bumps—or if there was debris all over the place in a cave, but the distance between pieces of debris where you are currently engaged is actually quite spacious.

On the other hand, if we're talking about a thick undergrowth of tangled vines, then yeah you're spending two maneuvers to do anything in that stuff

I say go for it! One wrong step and you might slip to your doom.

I say go for it! One wrong step and you might slip to your doom.

And here's your difficulty pool! *pushes 5 red Challenge dice forward*