If your OS uses Italian, Extension Manager will use Italian, too. If your OS locale is not Italian but you want Extension Manager use Italian, you can run command line:
1. Open Command Prompt Window (Windows) or Terminal (Mac).
2. Navigate to the Extension Manager application folder.
3. Enter the following command:
(Windows): ExManCmd.exe /launch "it_IT"
(Macintosh): ./ExManCmd --launch "it_IT"