The documentation for the plugin needs updating to match new configuration .
I for one am curious as to what "Search" stack size is for in CategoryStackMultipliers ?
And i can see too many people (like myself)  are not going to be impressed by the amount of editing needed in the new data config json !!
instead of this list (partial)

{
  "itemlist": {
    "8x Zoom Scope": 50,
    "Assault Rifle": 100,
    "Handmade Shell": 1000,
    "Pistol Bullet": 1000,
    "Incendiary Pistol Bullet": 1000,
    "HV Pistol Ammo": 1000,
    "5.56 Rifle Ammo": 1000,
    "Explosive 5.56 Rifle Ammo": 1000,
    "Incendiary 5.56 Rifle Ammo": 1000,
    "HV 5.56 Rifle Ammo": 1000,
    "Rocket": 20,
    "Incendiary Rocket": 100,​

We now have to go through a few hundred item numbers/durability (check whether yes or no) etc

{
  "ItemCategories": {
    "Weapon": [
      {
        "ItemId": 722955039,
        "Shortname": "gun.water",
        "HasDurability": true,
        "VanillaStackSize": 5,
        "CustomStackSize": 5
      },
      {
        "ItemId": -1815301988,
        "Shortname": "pistol.water",
        "HasDurability": true,
        "VanillaStackSize": 5,
        "CustomStackSize": 5
      },
      {
        "ItemId": 1789825282,
        "Shortname": "candycaneclub",
        "HasDurability": true,
        "VanillaStackSize": 5,
        "CustomStackSize": 5
      },
      {
        "ItemId": -363689972,
        "Shortname": "snowball",
        "HasDurability": true,
        "VanillaStackSize": 5,
        "CustomStackSize": 5
      },
      {
        "ItemId": 1103488722,
        "Shortname": "snowballgun",
        "HasDurability": true,
        "VanillaStackSize": 20,
        "CustomStackSize": 20
      },
      {
        "ItemId": 1569882109,
        "Shortname": "fishingrod.handmade",
        "HasDurability": true,
        "VanillaStackSize": 5,
        "CustomStackSize": 5
      },
      {
        "ItemId": 174866732,
        "Shortname": "weapon.mod.8x.scope",
        "HasDurability": false,
        "VanillaStackSize": 15,
        "CustomStackSize": 15
      },

The only thing you should modify in the data file is CustomStackSize. Everything else should not be touched and is auto generated and automatically maintained by the plugin.

If you're only setting a few overrides like your example, that needs done in the configuration file under Individial hard limits or multiplier.

Modifying the CustomStackSize in the data file is for more detailed control over stacks. I expect the vast majority of users to not touch the data file. Tools will be implemented to make this easier as well.

Documentation was updated, but some things are missing. I didn't understand the update process and accidentally sent an update before I'd even finished the description.

Documentation overhaul is my priority today. If anything else is confusing, or believe it needs changed let me know so I can mention it in the docs and get the QOL features implemented.