It would be nice to have a way to get a variable card corresponding to a block or item without actually needing that block or item in your inventory. I remember an old item transport mod that let you set item filters by selecting items from NEI/JEI, even if you didn't have them and weren't in cheat mode. Perhaps we could either do that, or just add an operator to get an item from a string (e.g., "minecraft:quartz_ore" -> Nether Quartz Ore).

You actually can use JEI for exactly this, by clicking on the + symbol on recipes.

But an operator like get_block_from_id or get_item_from_id might indeed be useful, will look into it.

Ah, I didn't know about that button, but I agree that having those operators would still be nice.