If contacting American Technology Components proves fruitless you can have a label maker make some up custom for you.
Contact Link:
https://www.atcomp.com/contact
What I did for my switches that have worn off letters was used my P-Touch Label maker with Clear Labels and played around with the font and size until I got something similar then trimmed it down to size and just stuck it on top. Still working find after a year.
We are all curious what you find out when talking with American Technology. If you don't mind posting what you find out and the results of what you end up doing.
Good luck!