I made an incredibly boneheaded mistake. I typed
diskutil cs create Fusion\ Drive disk1 disk2 instead of
diskutil cs create Fusion\ Drive disk0 disk1 (while I was looking at the list to make sure I did it correctly—sigh).
That's all I've done. I haven't actually gone ahead with the next step and reformatted the drive with:
diskutil cs createVolume logicalvolumegroup jhfs+ Macintosh\ HD 100%
To my understanding, the disks have not been reformatted.
Is it possible to reverse this and get all my data and previous disk formatting back without attempting data recovery (which would require splitting the disks anyway, I believe)?