Fiesta has a new publisher in NA and EU today. A quick visit to the Outspark website drops a new welcome page for gamigo with a message informing players that the publisher has assumed control of the license and operational duties for the game. Outspark has also ceased operation of its other titles.
The good news is that players with a balance of Sparkcash on their former accounts have had new ones created with gamigo and the balance transferred. Just expect some downtime for the migration to complete. You can get more details about the transition in the Migration FAQ.