Many Thanks. Success at last...
There were nuances in the format of the text file that I finally figured out!
Interestingly, "Clear Playing Now" is not in the English Languages.txt file. I added it as:
Clear Playing Now
Clear Playing
This worked.
Once again, thanks for the patience.
After getting the text file edited correctly, I had to enter the application and remove the default strings from the tool bar. I then restarted the app. and my changes were available to add to the tool bar.