Since the mod already gives people a button to manually craft the missing amounts, i would suggest the following:
A way to display either in the same menu or an extra one players can choose to open which displays the raw cost on what the player will need to craft all the missing ones. similar to how factorio shows raw cost in tooltips.

That's unfortunately a whole lot more complicated than simply crafting the missing item and is out-of-scope for this mod. It's basically its own mod. After all, how do you figure out which recipe to use when you have multiple different paths back to raw ingredients? If I need to ask players to pick recipes, then I'm basically re-making Factory Planner, which I'm not about to do. That's not to mention the fact that such raw ingredient estimates won't be that useful without taking into account productivity gains at different steps.