Startling font
https://www.dafont.com/startlingfont.font
Why Doesn't this font work with gimp?
What you really mean is: Why does the font not work on my installation?
As with your other post, not much information. What OS and version of Gimp?
Where did you install the font? It should go in your Gimp profile or for Windows can be installed with Windows fonts (never a good idea).
As the screenshot: Works in Linux and Win10, both Gimp 2.8.22 Linux I used my Gimp profile, Windows I installed into Windows fonts.
For windows Gimp did take some time starting, 'searching for fonts' Could be that your font cache is broken.
Never tried this, but recently someone got a fix by starting Gimp in 'administrative mode' and letting it start up
Otherwise you could try disabling the font cache and letting Gimp rebuild a new one.
see: https://www.gimp-forum.net/Thread-Windows-Gimp-loading-fonts-on-each-startup-possible-workaround
When I select it my font just looks like sans.
Sans is the default font used when a font is not available.
Example: You get a Gimp .xcf file from someone else. It contains text using a font not installed for you. All is fine until you try and edit the text. Text then reverts to Sans.