Okay, so this is weird. Either a bug or something I didn't know about the KickStarter...
In the Objects data there is LOOT_Kickstarter_Pouch_JoshuaSpice. In the ItemCombos there is LOOT_Pouch_JoshuaSpice. There is no LOOT_Pouch_JoshuaSpice in the Objects data. Given this I'd suspect we need to change the recipe data to use LOOT_Kickstarter_Pouch_JoshuaSpice as that is what you are holding.
Over on this thread
there's instructions on how to push a mod onto an existing savegame. I used those steps to make a couple proof of concept recipes in ItemCombos / ItemComboPreviews and they worked in my current save.
Then I went ahead and "fixed" the Joshua Spice recipes based on the bug you pointed out. That did the trick!
(I went ahead and made a recipe of carrot + pear to produce the spice, so I could test it with what I had on hand.)
So, technically we could fix them - or, well, add a whole bunch of new recipes for stuff that's "missing" - right now without waiting for Larian. But maybe that needs a different thread of its own...