the best chance to get them across on foot is to set the AI to safe mode, and in column formation, and then, very slowly cross the bridge, pausing constantly so the AI wont panic, of course, if you are taking fire, might as well go solo and leave the AI behind, the safe and column formation also applies to vehicles, they drive better on safemode
They should just do away with bridges altogether and create an isthmus or something.
Maybe they don't like BF2 troopers telling them what to do.
I'm not a programmer too, but I think that it shouldn't be so hard to make AIs to go from point A to B or to follow a leader.
First that AIs have no eyes, and the island and all of the objects are nothing more than an extense list of numbers, so everything happens in terms of numbers.
I think AIs get stuck sometimes cause they look to the point where the leader is before try to move until there, and there are some classes of objects, such as bridges that "blinds" its "visions".
The leader could leave "crumbs" in the patch: a list of coordinates that indicates to AI the point to step over.
If the leader step these points, obviously AI can step them too.
A counter should be triggered when a order "fall back into formation" was given, so any AI should be or in its position from the leader, according to the formation, or in one point from the patch "crumbs", and on the way to go next to the leader position.
If this counter reachs a specific number and AI is still stuck or far away from the destination point, a new counter should be opened for that AI. Them AI should consider a new temporary COLUMN formation and try step the crumb patch left by the leader.
So AI will not look to the point where leader is, but to the last point of the patch crumb and try to get there.