Title says it all. Ive been playing they are essentially in Reach of one another but then I got to thinking Close range would be good enough but on the other hand… could a Toughened leader run a squad of archers spread out over a larger area, as long as he able to command them? (Medium I guess with verbal commands etc.) The carry over of damage would seem to indicate they ahve to be in close proximity but I dont remember seeing anything about it in the rules.
I think it largely depends on flavor and narrative. A squad/mob of melee warriors tend to stay within reach of one another, but when they fight a single opponent, it makes sense that they surround and try to outflank her. Archers could be spread out more.
In any case, squads and mobs should remain all in the same zone. Otherwise attacking them is more complicated (and attacking players is more complicated as well). Imaging that some archers in the squad are in close range of the attacker and some are in medium range. This would mean that some archers have other Difficulty when attacking then others (because of different ranges). This defeats the whole purpose of a squad/mob that you have a group acting in unison with simple rules.
If you want to spread out beyond close range, you have to split your mob.