Currently under 1.12 (I playing with Skyblock Adventures modpack) Metallic grains is a waste product, has absolute no usage. Please let us produce some nuggets!

What do you have in mind?

In Not the Bees pack you can make different dusts from metal grains by just placing several patterns into carpenter (and this is how crystal grains work btw), I did not have a time yet to take a look if it's a change from your side or it's CraftingTweaks. But if it's CT, I'd definitely want to see similar, either converting grains to nuggets or dusts or whatever else. In a bee-based skyblock it is highly requried to be able make materials.

I can confirm that Not The Bees pack uses CT via Forestry mod extensions to create a diamond from morebees:graincrystal and some liquid:water

@glixyl graincrystal is the Crystal Grain, we talking about Metallic Grain. As I remember you can craft iron dust with 2-3 metallic grains.

thanks for the clarification and for the recipe i will use this recipe with CT to the same effect

Using MC 1.12.2 with MoreBees 2.0.1

This seems to be the case. However, you can clearly see the calls to add said recipes here:

https://github.com/Tencao/MoreBees/blob/1.12/src/main/java/com/tencao/morebees/recipes/RecipesCarpenter.kt#L55

And when I look at the decompiled source code of the download from Curse, I can see those same calls. Its very strange that they're not showing up in JEI.