The sound script is not packed into the right directory within the map. It should be packed in
maps, but instead it's packed in
C:/Users/Anakin/Desktop/koth_fiendish. TF2 won't load it unless it's in the right place.
I copied your soundscript into my maps dir and ran the map and can confirm the two muted sound names did not play, which is your intended result. You can use the console command playgamesound to conveniently play any cached game sound. This proves your soundscript works, so your problem seems to be related to packing. CompilePalX would have put the file in the right place for you.
I would have corrected the mistake myself and tested it but VIDE will not open the map, which I presume is caused by the Pakrat bug.
Tips
To mute a sound you only need to provide a replacement sound file parameter in the soundscript; you don't need to specify anything else like pitch.
Code:
"Announcer.RoundEnds10seconds"
{
"wave" "common/null.wav"
}
Your sounds and materials are in the root asset dirs. It's always best to place custom assets in their own subdirectory. e.g.
sound/mapname and
materials/mapname. This greatly reduces the risk of conflicts and potential application problems, and aids organisation down the line.