Has to be mono and .wav.wav sound files are less compressed and allow for a much more vivid short sound, as trying to make longer sound with .wav's will make the file stupid large.
And for regular sounds like in events? is there any other requirements?
Stereo sounds work. I have stereo sounds for a few of my private weapons, as well as some as independent sounds.
Blockland does not support stereo sounds properly, so idk what you think you're doing...
IIRC stereo works but doesn't fade out due to distance from sound, just stops at a certain radius.