As the title suggests, I think it would be highly beneficial for the "Search Recipes Using this Material" to have an option to filter completed recipes, similar to the actual Crafting Log. I personally have a tough time just deleting or selling materials because "I may need this later". Being able to see that a material is no longer needed for unique crafts would be a godsend!

Edit: If not an option, even just simply including a checkmark next to the item if it's been crafted before would be amazing.