In the Education Edition of Minecraft, gunpowder can be crafted using the new item sulfur, bone meal and either coal or charcoal. This is similar to the recipe that Cinderscapes has using its own version of sulfur, but I thought it could be a nice touch if you were to add bone meal to this recipe as a nod to the one in the Education Edition. I admittedly do not know if making gunpowder more difficult to craft would be detrimental to balance; this is simply an idea that can be discussed. For further parity, you could let coal be used in the recipe in place of charcoal, but I can understand wanting to restrict this to the rarer charcoal.