package us.blueeyemods.uem.config;

import net.minecraft.world.entity.EquipmentSlot;
import net.minecraft.world.item.enchantment.Enchantment;
import net.minecraft.world.item.enchantment.EnchantmentCategory;
import net.minecraftforge.common.ForgeConfigSpec;

import java.util.Arrays;
import java.util.List;

public class Config {
    public static final ForgeConfigSpec.Builder BUILDER = new ForgeConfigSpec.Builder();
    public static final ForgeConfigSpec SPEC;

    public static ForgeConfigSpec.EnumValue<Enchantment.Rarity> RARITY_ENUM_0;
    public static ForgeConfigSpec.EnumValue<EnchantmentCategory> CATEGORY_ENUM_0;
    public static ForgeConfigSpec.ConfigValue<List<? extends EquipmentSlot>> SLOTS_LIST_0;
    public static ForgeConfigSpec.ConfigValue<Integer> MAX_LEVEL_INTEGER_0;
    public static ForgeConfigSpec.ConfigValue<Boolean> TREASURE_BOOLEAN_0;
    public static ForgeConfigSpec.ConfigValue<Boolean> DISCOVERABLE_BOOLEAN_0;
    public static ForgeConfigSpec.ConfigValue<Boolean> TRADEABLE_BOOLEAN_0;
    public static ForgeConfigSpec.ConfigValue<Boolean> BOOKS_ALLOWED_BOOLEAN_0;
    public static ForgeConfigSpec.ConfigValue<Boolean> CURSE_BOOLEAN_0;

    public static ForgeConfigSpec.EnumValue<Enchantment.Rarity> RARITY_ENUM_1;
    public static ForgeConfigSpec.EnumValue<EnchantmentCategory> CATEGORY_ENUM_1;
    public static ForgeConfigSpec.ConfigValue<List<? extends EquipmentSlot>> SLOTS_LIST_1;
    public static ForgeConfigSpec.ConfigValue<Integer> MAX_LEVEL_INTEGER_1;
    public static ForgeConfigSpec.ConfigValue<Boolean> TREASURE_BOOLEAN_1;
    public static ForgeConfigSpec.ConfigValue<Boolean> DISCOVERABLE_BOOLEAN_1;
    public static ForgeConfigSpec.ConfigValue<Boolean> TRADEABLE_BOOLEAN_1;
    public static ForgeConfigSpec.ConfigValue<Boolean> BOOKS_ALLOWED_BOOLEAN_1;
    public static ForgeConfigSpec.ConfigValue<Boolean> CURSE_BOOLEAN_1;

    static {
        BUILDER.push("MENDING");

        RARITY_ENUM_0 = BUILDER.defineEnum("rarity", Enchantment.Rarity.RARE);
        CATEGORY_ENUM_0 = BUILDER.defineEnum("category", EnchantmentCategory.BREAKABLE);
        SLOTS_LIST_0 = BUILDER.defineList("slots",
                Arrays.asList(EquipmentSlot.HEAD, EquipmentSlot.CHEST, EquipmentSlot.LEGS, EquipmentSlot.OFFHAND, EquipmentSlot.MAINHAND), entry -> true);
        MAX_LEVEL_INTEGER_0 = BUILDER.defineInRange("maxLvl", 1, 1, 255);
        TREASURE_BOOLEAN_0 = BUILDER.define("isTreasure", true);
        DISCOVERABLE_BOOLEAN_0 = BUILDER.define("discoverable", true);
        TRADEABLE_BOOLEAN_0 = BUILDER.define("tradeable", true);
        BOOKS_ALLOWED_BOOLEAN_0 = BUILDER.define("isAllowedOnBooks", true);
        CURSE_BOOLEAN_0 = BUILDER.define("isCurse", true);

        BUILDER.pop();

        BUILDER.push("UNBREAKING");

        RARITY_ENUM_1 = BUILDER.defineEnum("rarity", Enchantment.Rarity.UNCOMMON);
        CATEGORY_ENUM_1 = BUILDER.defineEnum("category", EnchantmentCategory.BREAKABLE);
        SLOTS_LIST_1 = BUILDER.defineList("slots",
                Arrays.asList(EquipmentSlot.HEAD, EquipmentSlot.CHEST, EquipmentSlot.LEGS, EquipmentSlot.OFFHAND, EquipmentSlot.MAINHAND), entry -> true);
        MAX_LEVEL_INTEGER_1 = BUILDER.defineInRange("maxLvl", 3, 1, 255);
        TREASURE_BOOLEAN_1 = BUILDER.define("isTreasure", false);
        DISCOVERABLE_BOOLEAN_1 = BUILDER.define("discoverable", true);
        TRADEABLE_BOOLEAN_1 = BUILDER.define("tradeable", true);
        BOOKS_ALLOWED_BOOLEAN_1 = BUILDER.define("isAllowedOnBooks", true);
        CURSE_BOOLEAN_1 = BUILDER.define("isCurse", true);

        BUILDER.pop();

        SPEC = BUILDER.build();
    }
}

This works, but it seems to be a mess. How would I clean it up?

Not really a mess, so I would say there's no issue. Most you could do is change how you choose to implement the logic.