This feature is (sort of) already in, when you add an item in crafting menu only affixes available for that slot/item are shown.
Or is there a case where you want to see affixes you can craft for an item without having the item?
Anyway regarding search, I also had one (very minor) annoyance lately:
Affixes sometimes have different name in crafting menu vs on item.
For example on item you may have affix “Elemental Protection per equipped item with this affix” but in crafting menu it’s “Set Elemental Protection”.
You can use search term “affix” to find these affixes in shop/chest, but not in crafting menu.
You can use search term “set” to find these affixes in crafting menu, but not in shop/chest.
I’d like to have more consistency when searching affixes.