I am creating a mod for version 1.12.2 in Mcreator 2021.1

edit the recipe code. It's not that hard, you just set items for the recipe and then change their ID's in the code.

You can use Tags for Recipes.

Make A Recipe And Set Every Thing You Want In The Menu After You Name It If You Are Trying To Change Recipes For Biomes 'o' Plenty Make Sure You Look Up There Regeristry Name For There Recipe and Here Is The Code For Useing Tags 

Sorry For Typos I Only Have A Couple Min To Type This 

{
  "type": "minecraft:crafting_shaped",
  "pattern": [
    "012",
    "345",
    "678"
  ],
  "key": {
    "0": {
      "tag": "forge:nuggets/tin"
    },
    "1": {
      "tag": "forge:nuggets/tin"
    },
    "2": {
      "tag": "forge:nuggets/tin"
    },
    "3": {
      "tag": "forge:nuggets/tin"
    },
    "4": {
      "tag": "forge:nuggets/tin"
    },
    "5": {
      "tag": "forge:nuggets/tin"
    },
    "6": {
      "tag": "forge:nuggets/tin"
    },
    "7": {
      "tag": "forge:nuggets/tin"
    },
    "8": {
      "tag": "forge:nuggets/tin"
    }
  },
  "result": {
    "item": "thunder_island:tin_ingot",
    "count": 1
  }
}

{
  "type": "minecraft:crafting_shapeless",
  "pattern": [
    "012",
    "345",
    "678"
  ],
  "key": {
    "0": {
      "tag": "forge:cobblestone"
    },
    "1": {
      "tag": "forge:cobblestone"
    },
    "2": {
      "tag": "forge:cobblestone"
    },
    "3": {
      "item": "minecraft:lava_bucket"
    },
    "4": {
      "tag": "forge:gears/iron"
    },
    "5": {
      "item": "minecraft:water_bucket"
    },
    "6": {
      "tag": "forge:cobblestone"
    },
    "7": {
      "tag": "forge:cobblestone"
    },
    "8": {
      "tag": "forge:cobblestone"
    }
  },
  "result": {
    "item": "thunder_island:cobblestone_gen_block",
    "count": 1
  }
}

This generator is no longer supported.