apparently simplified chinese locale is called "zh-Hans" in .Net framework.

ArcFormats/ArcFormats.csproj

@@ -304,7 +304,7 @@
     <Compile Include="YuRis\ImageYCG.cs" />
     <Compile Include="Zyx\ArcBDF.cs" />
     <Compile Include="Zyx\ImageSPL.cs" />
-    <EmbeddedResource Include="Strings\arcStrings.zh-CN.resx" />
+    <EmbeddedResource Include="Strings\arcStrings.zh-Hans.resx" />
     <None Include="ArcSeraph.cs" />
     <Compile Include="ArcSPack.cs" />
     <Compile Include="NitroPlus\ArcSteinsGate.cs" />

GUI/GARbro.GUI.csproj

@@ -229,7 +229,7 @@
     </EmbeddedResource>
     <EmbeddedResource Include="Strings\guiStrings.ru-RU.resx" />
     <EmbeddedResource Include="..\LICENSE" />
-    <EmbeddedResource Include="Strings\guiStrings.zh-CN.resx" />
+    <EmbeddedResource Include="Strings\guiStrings.zh-Hans.resx" />
     <None Include="packages.config" />
     <None Include="Properties\app.manifest" />
     <None Include="Properties\Settings.settings">

GameRes/GameRes.csproj

@@ -88,7 +88,7 @@
       <LastGenOutput>garStrings.Designer.cs</LastGenOutput>
     </EmbeddedResource>
     <EmbeddedResource Include="Strings\garStrings.ru-RU.resx" />
-    <EmbeddedResource Include="Strings\garStrings.zh-CN.resx" />
+    <EmbeddedResource Include="Strings\garStrings.zh-Hans.resx" />
   </ItemGroup>
   <ItemGroup>
     <None Include="packages.config" />