Lily pads sound like stone when jumping on top of them

Lily pads not having placement sounds has already been reported at MCPE-114160. Updating this report to only be about the walking sounds.

Also affects scaffolding and boat entity

This is actually caused by the block sound assigned to water. Changing the "sound" property of "water" in blocks.json changes the step sound you hear on Lily Pads. This is likely why it also affects boats.

For scaffolding, I would have to guess the same thing is happening with the "air" block.