Luxembourg is mentioned in Kennilworthy Whisp’s book Quidditch Through the Ages as a country where the players exhibit a high standard of Quidditch skill, such as strategic moves and goal-scoring ability (QA8).
Although Luxembourg fields a National Quidditch side, there is no mention on its Wikipedia page of Quidditch or any other wizarding sport (Wikipedia).
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: Luxembourgian National Quidditch Team