The sculk sensor is able to detect footsteps and gives signal strength 1. And jump up or down a block gives strength 5. Interactions with scaffolding are inconsistent:

• Walking across scaffolding gives strength 1 (except with bug MC-212583) (expected)
• Jumping up, or going down 1 scaffolding near edge gives gives strength 5 (expected)
• Crouching down 1 scaffolding in center gives strength 1 (not expected)
• Holding jump to go up any number of scaffolding in center gives strength 1 (not expected)
• Crouching down multiple scaffolding is not detected but subtitles say "footsteps" (maybe expected because "sneaking")
• Holding jump and crouch and moving around is not detected (also says footsteps in subtitles), though the player is making plenty of sound (not expected)

Ultimately it seems like player vertical movement is not detected consistently, and sneaking always makes movement noise neglected unless they release crouch mid decent. It could also be that the sound and subtitle should not play while crouching altogether. With enough time the player can get used to these settings, but it is not intuitive as is.

Attached is video demonstration of the 6 different scenarios.