I was playing BT Trilogy via GOG Galaxy. Today the client "failed to update", and after that all my cloud saves are gone!
Needless to say how happy I am...
There does not seem to be any backup in the local install folder.

The exact same thing happened to before, but with a different game (Darkest Dungeon).
What can I do? Are my savefiles gone forever?

OK, here's what probably happened:
GOG applications and COMODO Internet security probalbly won't get along.
The antivirus got a bit too aggressive, and after GOG was updated it did not let BT Trilogy write its own folder.
I had to check and unblock BT Trilogy.
I hope it won't happen again, but my saves are still gone. Both from the cloud and from the AppData local folder.