There has been a discussion about licenses of STK sfx recently, and there seem to be some files which have problems. I didn't know what to look for exactly, so I just took the first file which had "???" anywhere: "anvil.ogg"
Here is my first attempt making a sfx. Looking forward to you comments. (If you try it, make sure to make a backup of the original.)
If you consider this any good, I'll release it under CC0 and if there are other sfx that would need a replacement (due to license issues), then I'd be happy to try to see if I can come up with something useful. I'm not exactly sure what to look for in the licenses.txt though.
I don't say my version is better than the original one. If there is no (serious) license problem with the current "anvil.ogg", that's just fine.
UPDATE: I've updated the file and will keep the latest version here, so you don't have to scroll down. I hope that's a good thing to do.