How to: Locate your save files
Save files can be located at the following locations:
X:\Program Files (x86)\Steam\userdata\Your User ID\230190\remote
~/Library/application support/steam/userdata/Your User ID/230190/remote
~/.local/share/Steam/userdata/userdata/Your User ID/230190/remote
You will need to add both the save file & the meta file.
These save files will not have the display name that you gave them whilst saving, they will reference the level and a timestamp:
4 bonus round cornucopia_20180418165553
4 bonus round cornucopia_20180418165553.meta
If you have multiple saves with very similar names, then simply sort you save files by date and you should be able to find you most recent that way.