In the folder that you identified in Step 2, look for the following files: TripleTownData.dat and TripleTownData_backup.dat. Rename both TripleTownData.dat and TripleTownData_backup.dat to something else temporarily (e.g., OldData.dat and OldData_backup.dat).
Put the TripleTownData.dat file you want to use into the folder that you identified in Step 2. (You are essentially swapping out the old TripleTownData.dat that was in that location with the new TripleTownData.dat that you desire to use.)
Start Triple Town. The game should load the replacement data file.
Prior to launching the game, Steam may inform you that there is a conflict between your local save file and your cloud save, and ask you which you'd like to use. If this happens, choose to use the LOCAL FILES.
If you are still loading from the original file, the problem is possibly that you didn't rename both files in Step 3.
If all goes well, delete the files you renamed in Step 3.