They could fix sieges right now with tools already clearly available to them.
All they need to do is take the time to recode the pathing so that soldiers don't all try to climb the ladders at once. Make it a specialty assignment like breaking the inner gate, or setting up the ladders, and you're done. The buulk of the ladder detachment could stand in formation 3 paces from the ladder while selected Soldiers would move to the ladders as assigned by the same algorithm that picks who gets to push the battering ram, the only problem then would be fine tuning the algorithm so that a steady stream of soldiers climb the ladder at any given time.
Right now, we have a moshpit at the bottom of ladders and there's so much pushing and shoving that no one can get to the exact point to start climbing. That's why we have this problem. So the other solution is just to make ladder collision easier by widening the area where troops attach to ladders, so you don't have to be standing in exactly one place to start climbing and the jostling isn't as disruptive to the climbing. That would also fix things.
either way, like I said, the tools are already in place and the fix should have been out months ago. It's not rocket science. I can only conclude that they're not diagnosing the problem correctly.