FeralHeart will only read files contained within the FeralHeart folder and all subfolders.
If you think there's a possibility that FH might be reading a stray file somewhere, a quick way to try and find it (if you have Windows, which I'm hoping you do) is to put an asterisk in the search bar and hit enter,
which will bring up ALL files in the FeralHeart folder and subfolders. Then you can right click on the results and sort by type,
and then just scroll down until you start finding jpgs and pngs, and see if anything matches that texture. Which I believe would be called CeilingTex, but it's possible it could be something else.