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.
Customer support service by UserEcho