If any individual sounds should be WAI or duplicate, let me know and I'll cross them off this ticket. If it's all WAI or duplicate, well, oops! Sorry. I hope this doesn't sound like a feature request, because I do legitimately believe this is an oversight.

Jukebox: MC-200484
Weighted pressure plates: MC-6897
Redstone: Uses the sound of solid stone, despite being a powder. It seems this one should use the sand sound
Redstone comparator, repeater, and lever: Uses the wood sound, despite the base being made of stone and cobblestone, respectively.
Cauldron: Uses the stone sounds, despite metal blocks using the metal sound, and hoppers, a very similar block, also using the metal sound
Cobwebs: Stone? That doesn't seem right. I think wool sounds would fit. 
Tripwire hook: Sounds like stone despite the base being made of wood.
End rod: Sounds like wood, despite blocks made of its base (popped chorus fruit) using the stone sound, implying popped chorus fruit is very hard. Also blaze rods strike me as pretty hard too.
String: It uses the stone sounds. It's a little piece of string....

Will update if I find any more blocks that use an objectively incorrect sound.