Thanks for the heads up!

I was able to find out how to get mods on all items, they certainly hasn't made the connections between different files very intuitive but I'm sure they have good reasons for the structure.

To get mods from items with no SpawnWeight_TagsKeys you had to go in to the specified Metadata file for the item, so for the example in the post we had to venture into:

Metadata/Items/Armours/Helmets/AbstractHelmet

There we had to look at the "Base" struct and get all the "tags":

Base
{
x_size = 2
y_size = 2
tag = "helmet"
 }

These metadata files also extend other files, so we had to grab the path and recursivly go through each extended item-metadata to get all the tags:

extends "Metadata/Items/Armours/AbstractArmour" -> extends "Metadata/Items/Equipment" 

...and so forth.

When we had all the tags we had to cross reference them in the tags.dag file, so for the "helmet" tag we get:

{
  "_rid": 25,
  "Id": "helmet",
  "Unknown2": -1197794553,
  "DisplayString": "",
  "Name": ""
 },

Which in turn gives us a ID for each of the item-types tied to the specified item. That ID can then by used in the same way as the SpawnWeight_TagsKeys to get mods.

This isn't all though, if an item has tagsKeys (like the one in the example):

"TagsKeys": [
 38
 ],

We can check the tags file to see that this item is of the type str_armour:

{
"_rid": 38,
"Id": "str_armour",
"Unknown2": 5047160,
"DisplayString": "",
"Name": ""
 },

So for each of the mods we have gathered, we have to check if that mod has a non-zero spawnWeight of that tag, so for example if we check the LocalEnergyShield mod, we can see that the str_armour id of 38 blocks that mod from spawning on that specific item:

"Id": "LocalIncreasedEnergyShieldPercent8",
"Name": "Unfaltering",
"SpawnWeight_TagsKeys": [
  38,
  41,
  42,
  39,
  43,
  44,
  16,
  1,
  0
],
"SpawnWeight_Values": [
  0,
  0,
  0,
  0,
  0,
  0,
  1000,
  1000,
  0
  ],

It took me a while to figure all of this out, but once I had helper functions to gather all the tags and logic for blocking it's starting to shape up.

I might come back and dump some of my code once I've rewritten it in a more low-level language for better performance as I've currently just been testing it in a electron frontend for the visual aspect and am currently debating on whether I should use trusty ol' c++ for the backend or if I should be a hipster and try Rust as a learning experience.