When a calibrated sculk sensor is calibrated to signal strength 11, it's supposed to detect block changes according to the wiki. I placed a calibrated sculk sensor with a comparator facing into its input side (where the purple vein is located) and a hopper pointed into the back of the comparator. The hopper has 3 wooden swords and 37 sticks in it to produce a signal strength of 11.

When a sheep eats grass, the CSS does not detect the grass changing into dirt. When the dirt turns back into grass, it also does not detect that change.

Edit: It also does not detect copper blocks changing when they oxidize.