Synchronised swimmers will often have elaborate costumes. These costumes are used to highlight or emphasise the theme of the music. Costumes are not judged and so should not affect the scores.
If a head dress falls off one of the athletes in the British team, they get a fine because experienced athletes should ensure everything is securely fastened.
Synchronised swimmers also wear make up. The make up will be used to highlight the swimmers features so it is easier for the judges to interpret their facial expressions. It should not be so theatrical that it is distracting.