Translating GUI

See https://jetbrains.org/intellij/sdk/docs/reference_guide/localization_guide.html .

Thanks, but I've already read that.

Let's assume that all the translations are in this folder. 
What do I do with them? I should create a plugin. I tried to "copy" the structure of the Chinese Language pack but it's not working.

Have you ever tried to do such thing?

Please share the plug-in jar that is not working: https://uploads.jetbrains.com.

I sent the project structure but I removed the ".iml" file and the ".idea" and the "out" folders.

Upload ID?

Upload id: 2020_11_09_4bTMcGzckPkmLbGG (file: Italian Translation.zip)

META-INF\plugin.xml is missing, check the one for other translations as an example and make your own.

<extensions defaultExtensionNs="com.intellij">
  <languageBundle lang="zh"/>
</extensions>

How is that possible? I created plugin.xml file. Its path is resources\META-INF\.

In the files you shared it appears in the resources subdirectory. You need to actually package the plug-in into the jar file so that the files are placed in the correct locations.

See https://jetbrains.org/intellij/sdk/docs/basics/getting_started.html and https://jetbrains.org/intellij/sdk/docs/basics/getting_started/deploying_plugin.html .

Is this structure correct?

It depends how you package the plug-in. If you just zip it and rename to jar, it may work, but the proper way how to structure and package the plug-in is described in the documents I've linked above. Just compare the final layout to one of the working plug-ins to see what's wrong.

This structure is right: the translation plugin works!

I did the deploy like this:

Thank you for your support and for your patience.