Take your song mappings to another device—or bring them back after Reset—without touching the Fantom backup tree.
Save and load songs to a folder on your device or the cloud with Share and Load. Do not save that file inside /ROLAND/FANTOM/BACKUP or its subfolders. Your Fantom will not like that and may flag your USB stick as unavailable!
1
Share / Save
Tap Share on the Songs screen and pick a folder on your device or in the cloud.
2
Load
Tap Load and choose a Songs file to bring mappings onto this device (for example after Reset, or when setting up another phone).
Share and 
Load. Do not save that file inside 
