I made a taunt editor and it works for me in the current version of soldat (1.4.1). I've used it so i know it does. I don't feel like finding where i posted it, so i'll tell you another thing: when you save the taunts.txt file, you should make sure that the codification isn't ANSI, but UNICODE. (you can choose that in notepad when you are about to save the file).
And also and very important, restart soldat after editing the file, because it doesn't load magically when u edit it.