Hi there! I can’t find the quantities for salt and peppercorns. Do the quantity matter? I also agree with previous comment:do we crush the peppercorns

The key when ingredients are missing from a particular recipe and you get no response (from recipe author or site) is to look elsewhere for a similar recipe.
Another recipe for this salted duck (not the one on food52) calls for 4 tbsp salt and 2 1/2 tbsp Sichuan peppers (whole, not crushed).
If you want to be really thorough, look at two or three other recipes, to catch variations of ingredients or proportions.