Challonge's support for multi-stage tournaments has always been "incomplete" to say the least; the API support for those types of tournaments are even more incomplete. When you tried to submit a multi-stage tournament to XenTorneo, it would always result in an error. With this update, you will no longer receive an error. Instead the system will simply ignore the unsupported results and matches and allow you to submit the final stage of the tournament as a bracket.