I couldn't find a 'clean' way to do this, but if your text is static you could use css.
First, make a style class. For the example, I called mine addtext.
If you're on the last version, with the new css sheet, add this:
.psc-addtext::after {content: " your text";}
If you're on an older version, you can the theme file, or css injection.
If using theme file, add the same line as above in your .css
For injection:
In your style class, pick a property with a text field, for example background image, and add this:
} .psc-addtext::after {content: " your text here"} {
Now, apply that style class to the progress bar's valueDisplay style:
And you're done:
