All of the above does seem to happen quite frequently, as well as Crota falling off the centre platform above to chase the sword carrier. He then seems to teleport back up to the top, surely you can just identify the regions that Crota patrols within and prevent this from happening. The only foreseeable way to stop some of the bugs from happening is to completely go back out of the raid to orbit and then re-load the game. Another bug we have is the sword literally vanishing as soon as the swordbearer is taken out.