Originally Posted by PatrickSJ
Basically you also want:

The first 4 define the items, their types, categories, etc.
DeltaModifiers sits between maps a Boost from ItemCombos to an entry in the first 3 files.

Alright, so thanks to this tip I started snooping into the TXT files that those generate. (The XLSM's aren't needed for anything but convenience.)

I had been wondering for awhile why the fish + oven recipe wouldn't give me dinner, and why fish + dough seemed to ignore most fish.

Potions.txt seems to have the answer. It has a bunch of entries like this:

new entry "FOOD_FishA"
type "Potion"
using "_Food"
data "Act part" "1"
data "StackId" "Intelligence"
data "ComboCategory" "FoodFish"
data "Weight" "200"
data "Value" "2"
data "Intelligence" "1"
data "Speed" "-1"
data "Duration" "3"

However, when I pop into the Engine and search for fish in RootTemplates, the names are in the form of CON_Food_Fish_A.

I am going to permit myself just a bit of a rant here and declare my astonishment that a game engine actually depends on plain text files for so much of its logical structure. The fact is, it will inevitably lead to exactly this kind of bug. Things get renamed all the time in large projects (usually as part of "refactoring" during a late optimization phase, when many dependencies now exist), and unless those things are logical objects with singular definitions and a referential structure, it becomes incredibly difficult to ever rename anything or, for that matter, to completely eliminate human error in the form of ordinary typos. I remember when I had this problem working on large bodies of code before modern IDE's provided tools for refactoring... like, in the 90's.

End rant and now I have to decide if this mod is going to fix Potions.txt as well. That's quite possibly a file that other mods are going to want to touch though, so I'll probably just have to wait for Larian on this one. :\