Sorry to hear that. I hope none of them were full of vital data.
If they were, you can probably get them restored through Apple's Tech Support. If you have a current AppleCare subscription, it's free. Otherwise, you're really going to have to want those spreadsheets badly, because it will cost.
I've never used Apple Tech Support to restore files, but I came close once. I'd lost all my iCloud documents, and called support in hopes that the restore would be easy. The tech said it could be done, but would require a ticket to the server support people, and take a couple of days. Since I had all the documents backed up in TimeMachine (as I previously described), I chose to restore them locally on the iMac instead, and see if they would sync back to iCloud. They did.
Ironically they all went away and then re-appeard a couple days later. My guess is that the iCloud Documents glitch was more than me, and I got caught between the general data loss, and Apple's more comprehensive restoring of their serves.
I lost nothing of importance when this happened, but I could have used the same TimeMachine method to recover if I had.
And as I've mentioned, all my most important documents get sent to Box.com, so those were never at risk to begin with. The downside of this is that it is manual. I have to remember to send a copy to Box every time I edit the documents.