Other canon notes and references
Since Viktor Krum, born 1976, was the oldest player at the tournament (QWC), Boigny must have been born after 1976.
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 timeline of Quidditch
Lexicon lists of:
From the Web
Writing by J K Rowling on WizardingWorld.com (Pottermore): The Daily Prophet
Writing by J K Rowling on Imgur (Daily Prophet coverage of the 2014 Quidditch World Cup, originally from Pottermore):
- History of the Quidditch World Cup
- Quidditch World Cup 1990-2014
- Match reports and articles from the 2014 Quidditch World Cup
Harry Potter Wiki: Sylvian Boigny