Seems pointless to have macros for this when an ingame mechanic could replace it pretty easily. Due to how ore is cooked by players wheelbarrowing coal doesn't fill this need, so why not the humble shovel?
If character has shovel equipped:
Right clicking on a coal stockpile shovels up 12 coal if the shovel has less than 12 coal loaded
Right clicking on a smelter with the shovel adds in 12 or 9 if all the ore inside require 9 to cook
Right clicking on ground empties the shovel and creates a new stockpile