Oh, right! Just out of curiosity: would that imply that amongst those who downloaded your patch, there’re many more people using WLM (Plus! 4) compared to the userbase of MSN 7.5 (Plus! 3)? Given the fact that while searching among Plus! 3 public sounds it was able to find only one.
Well, I’ve just tested it out and seems like random sounds search is working. 
I was able to find a bunch of new sounds, even one that I’ve created myself!