Other canon notes and references
Sylvian is derived from the word sylvan meaning "wooded, associated with woods" and is related to the Latin word silva meaning "wood, forest" (Oxford English Dictionary). The more common spelling of the name in French is Sylvain "man of the woods" (Baby Namespedia). The other possibility, particularly if Sylvian Boigny is female, is that the name is a combination of Sylvia and Ann.
The surname Boigny is shared with the first President of Ivory Coast, Félix Houphouët-Boigny (1960-1993) (Wikipedia).
There are two Seekers in the 2014 Quidditch World Cup tournament with the unusual name of Sylvian - Sylvian Boigny from Ivory Coast and Sylvian Jolicoeur of Haiti, although the latter is definitely a male.
Lexicon list of Seekers
From the Web
Writing by J.K. Rowling on Pottermore:
- History of the Quidditch World Cup
- 2014 Quidditch World Cup reports
- 2014 Quidditch World Cup final
- The Daily Prophet
Pottermore enhanced reading experience: Quidditch World Cup
Screenshots of the original Daily Prophet coverage of the 2014 Quidditch World Cup on Pottermore: Imgur archive
Harry Potter Wiki: Sylvian Boigny