Are teams allowed to modify robots between qualifiers and World?
There are no limitations on modifying robots between events, the only limitation are modifying a robot DURING the event, and still you can make some minor changes to the robot as long as they are minor changes, any mayor changes you would have to take it back to the inspection booth to get it inspected again, but once the event is finished you are free to make as many modifications as you want in order to continue improving for the next event.