What is balancing a system?
In most heating systems all of the radiators are on at the same time, and so the system must be balanced to stop the first few radiators using all the hot water, leaving those at the far end of the system from ever getting hot or taking a long time. This involves individually adjust the lock shield valve (at the opposite end of the radiator to the TRV) so water is spread out more evenly.
How does Genius Hub affects this
In many cases the Genius Hub system is more resilient to poor balancing. With the Genius Radiator Valves, instead of every room being heated now only some of them are, and the Genius Radiator Valves will adjust to just the right position individually knowing how open the valve needs to be to get hot water. However this does not negate the system being balanced properly by a heating engineer, because if some radiators are turned right down on their lock shields then the Genius Radiator Valves will not be able to compensate for that.