I just want to make a note that yes, deletion is final and will delete previously saved content
There is never a change saved unless you save the song, clearing is the only case where saved content could be lost or altered in a saved song.
Clearing the song using Play Stop all is an undoable action
To help avoid losing the state of a song we have implemented a Copy feature in the 5.0.0 beta, now you can copy a song before making more changes to it.
Copies only retain saved progress, unsaved progress will not be copied.
Thanks for your questions and feedback