>>72703012you can the X part in [sound=X] through a URL Escape decoder
https://www.urldecoder.org/to get the link to the raw audiofile, which might contain metadata like title, album, artist etc.
So with this
fuwamoebius [sound=files.catbox.moe%2Fjhfggy.mp3].png
you'd decode
files.catbox.moe%2Fjhfggy.mp3
to get
files.catbox.moe/jhfggy.mp3
Most of the time its just the singe %2F that needs to be replaced with a /
And if you open the file in a media player and inspect the meta-data you get pic rel.