Requirement
ObjectARX, .NET, and ObjectDBX modules
You should add your resource files under respective language folder. In AutoCAD, resource files follow a standard naming convention, for example xxxres.dll. If it is English, you should add the resource file under en-US in the root directory. For example:
C:\Program Files\Autodesk\AutoCAD 2021\en-US
For Japanese language pack you should add the resource file under jp-JP folder in the root directory. For example:
C:\Program Files\Autodesk\AutoCAD 2021\jp-JP
For different language products, mostly the resource files are different. By adding the resource files under corresponding language product root directory enables Language Pack--if you already have the English version of AutoCAD, when you install Japanese AutoCAD, you only need to install the Language Pack; no need to install the whole product again.