Steil-Antoni has played for team Luxembourg in the 39th Chess Olympiad, the Women's Chess Olympiad, the 2011 European Team Chess Championship, and the European Small Nations Team Chess Championship. She was part of the team that won the bronze medal in the 2009 European Small Nations Team Chess Championship, held in Andorra la Vella. In 2006, at the Women's Chess Olympiad in Turin, she won the individual gold medal on board two thanks to a score of 10/12 points. She was awarded the Woman FIDE Master (WFM) title for this result.