OK, here we go:
Here you’ll find the whole picture of how to find not only SSiW but all app files (MP3 in this case) on Android. Instead of clicking on the com.saysometnihgin.welsh folder you click on any other folder to find other applications data in there.
Staying with SSiW app this is it. HAPPY BROWSING.
Now, later I’ll test what happens when you move those files to elswhere.
Enjoy!