There's one more option for failover, though our documentation states transcoding is recommended even for this case, it is not mandatory.
You can use Server's playlist with two live streams, with one specified as DefaultStream. The DefaultStream will be used as fallback stream, and the second defined in a playlist stream will be main.
Please find a technical description of Server Playlist functionality, on the following page:
If you need more details or face any difficulties with the mentioned setup, please open a ticket at wmspanel.com/help