I didn't notice any bug. But checking the debugger that 1 sound plays ~20 times at once. No sound is going to sound good 20 times at once.
Part of it is the sound itself has a long tail, so lots of opportunity to overlap and cause phasing issues. You should probably just use a much shorter sound, like 0.2 seconds. But to kind of fix it I did 2 things, first I simply cut the last 1 second out and added a fade out. Second I used a high pass filter to cut out the bass frequencies below 200 hz (sometimes if a bunch of low bass builds up it muddies up the sound).
Next I modified your events to limit the number of times a single sound file can play simultaneously. I did that using a dictionary. When a sound is played, I add it to the dictionary with the file name as the key and count the value up. When the sound ends I subtract 1 from that key. If the count of a specific sounds gets above a threshold then I just stop playing it until enough sounds end.
It sounded a bit better after I did those 2 things. I hope that helps!