I know it's a super old question... anyway:

The text inside the progress bar has been removed from GTK 3.14. If you would like to see it inside (GTK 3.14+ and GTK 4.0+), you have to use negative margins and min-heights.

The double text color has been removed from GTK 3.8. If you would like to have it, you need to patch GTK (gtk3.patch [incomplete, but it works], gtk4.patch - [not working, please help!]).

Example with human theme with GTK 3.24-classic :