By using the /preferreduilang compiler option, you can specify the language in which the C# compiler displays output, such as error messages.
Syntax
/preferreduilang: language
Arguments
language
The language name of the language to use for compiler output.
Remarks
You can use the /preferreduilang compiler option to specify the language that you want the C# compiler to use for error messages and other command-line output. If the language pack for the language is not installed, the language setting of the operating system is used instead, and no error is reported.
csc.exe /preferreduilang:ja-JP