Kammala jumla mai zuwa: Fiala ya taka leda a gasar tunawa da Ivan Hlinka a 2012 da 2013 a matsayin memba na kungiyar U18 ta Switzerland. Ya kuma yi wasan skate don kasarsa a gasar
2014 Gasar Hockey ta Junior ta Duniya, inda aka yaba shi a matsayin daya daga cikin manyan 'yan wasan da ke cikin jerin' yan wasan Switzerland. A cikin wasanni biyar na WJC, ya zira kwallaye guda ɗaya da taimako huɗu, yayin da Kanada ta fitar da Switzerland a wasan kusa da na kusa da na karshe. A watan Mayun 2014, Fiala ya wakilci Switzerland a Gasar Cin Kofin Duniya ta IIHF ta 2014 a Belarus, inda ya yi rajista sau biyu a wasanni bakwai. Fiala shi ne dan wasa na uku a tarihi da ya taka leda a gasar zakarun duniya na 'yan kasa da shekaru 18, da kuma gasar cin kofin duniya a shekara guda (na farko biyu sune Andrei Kostitsyn da Vadim Karaga, duka tare da Belarus a 2003). Fiala ya kuma halarci gasar cin kofin duniya ta IIHF ta 2018, inda Switzerland ta lashe azurfa. A wasan karshe da Sweden Fiala ya samu damar lashe zinare a karin lokaci amma harbinsa ya yi kasa sosai. Bayan rasa wasan harbe-harbe, 'yan Switzerland sun gamsu da azurfa.