The one bunk on top of the cabinets would be easy to reinforce; hide bracing inside the cabinets (pull out the drawers, put in some 1x4 or 2x4 jack studs, more maybe bracing across the bed first, and then jack studs under that, running down to the floor. perhaps put a piece of wood under the jack studs as well, in case the plywood floor is thin.
The bunk that appears to just be floating on the wall (on the right), no pretty way to reinforce that one... can't imagine it holding anyone but a baby or small toddler.