Been messing with this lately. Oddly enough when you load your own sounds in, it plays back really fast when you use 'Play Sound', but when I reextract the wav, it sounds ok (albeit lower quality; but that's to be expected). It also sounds ok when it plays inside the game, so it's whatever I guess.
There's another issue that's a little more concerning. I loaded in 2 custom sounds at ID 10641 and 10642. I then loaded in 9 more sounds at 10643 - 10651. I went back and added descriptions for each of these files so I wouldn't have to painstakingly go through them to remember what they were. I then added 5 more sounds from 10652 - 10656. The instant I did that the descriptions for 10643 - 10651 got deleted. It didn't delete the sounds though. But at the same time this happened, the descriptions for 10641 & 10642 were left untouched. So that's an annoying bug. I had to go back and re-add all of those descriptions. I'm gonna try to avoid symbols and just stick to text, and maybe put some gaps in-between mass imports once I do my next batch, but if it keeps doing this, the descriptions column might be completely unusable.
EDIT: I realized after returning to my project many months later that I had simply left sound files in the import folder while trying to add more. So anyone who uses this, just keep in mind any time you replace or re-import a sound, it'll erase any notes/descriptions you included in that cell for the old sound (which makes sense why it would do that, but just a heads up since it's an easy mistake to make).