mixin to locale and I18n to access the key map directly to fix LangKey

src/main/java/gregtech/api/mui/LocaleAccessor.java

@@ -0,0 +1,19 @@
+package gregtech.api.mui;
+
+import net.minecraft.client.resources.Locale;
+
+public interface LocaleAccessor {
+
+    String gregtech$getRawKey(String s);
+
+    ThreadLocal<LocaleAccessor> accessor = new ThreadLocal<>();
+
+    static String getRawKey(String s) {
+        if (accessor.get() == null) return s;
+        return accessor.get().gregtech$getRawKey(s);
+    }
+
+    static void setLocale(Locale locale) {
+        accessor.set((LocaleAccessor) locale);
+    }
+}

src/main/java/gregtech/mixins/minecraft/L18nMixin.java

@@ -0,0 +1,20 @@
+package gregtech.mixins.minecraft;
+
+import gregtech.api.mui.LocaleAccessor;
+
+import net.minecraft.client.resources.I18n;
+import net.minecraft.client.resources.Locale;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(I18n.class)
+public abstract class L18nMixin {
+
+    @Inject(method = "setLocale", at = @At("HEAD"))
+    private static void getLocale(Locale i18nLocaleIn, CallbackInfo ci) {
+        LocaleAccessor.setLocale(i18nLocaleIn);
+    }
+}

src/main/java/gregtech/mixins/minecraft/LocaleMixin.java

@@ -0,0 +1,22 @@
+package gregtech.mixins.minecraft;
+
+import gregtech.api.mui.LocaleAccessor;
+
+import net.minecraft.client.resources.Locale;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.Map;
+
+@Mixin(Locale.class)
+public abstract class LocaleMixin implements LocaleAccessor {
+
+    @Shadow
+    Map<String, String> properties;
+
+    @Override
+    public String gregtech$getRawKey(String s) {
+        return this.properties.get(s);
+    }
+}

src/main/java/gregtech/mixins/mui2/LangKeyMixin.java

@@ -0,0 +1,20 @@
+package gregtech.mixins.mui2;
+
+import gregtech.api.mui.LocaleAccessor;
+
+import com.cleanroommc.modularui.drawable.text.BaseKey;
+import com.cleanroommc.modularui.drawable.text.LangKey;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+@Mixin(value = LangKey.class, remap = false)
+public abstract class LangKeyMixin extends BaseKey {
+
+    @Redirect(method = "getFormatted",
+              at = @At(value = "INVOKE",
+                       target = "Lnet/minecraft/client/resources/I18n;format(Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;"))
+    public String getTranslateKey(String translateKey, Object[] parameters) {
+        return LocaleAccessor.getRawKey(translateKey);
+    }
+}

src/main/resources/mixins.gregtech.minecraft.json

@@ -18,8 +18,10 @@
   "client": [
     "BlockMixin",
     "EntityRendererMixin",
+    "L18nMixin",
     "LayerArmorBaseMixin",
     "LayerCustomHeadMixin",
+    "LocaleMixin",
     "RecipeRepairItemMixin",
     "RegionRenderCacheBuilderMixin",
     "RenderChunkMixin",

src/main/resources/mixins.gregtech.mui2.json

@@ -8,6 +8,8 @@
     "maxShiftBy": 10
   },
   "mixins": [],
-  "client": [],
+  "client": [
+    "LangKeyMixin"
+  ],
   "server": []
 }