I started programming when I was 9 years old. I basically learned my first English from Pascal's syntax and APIs (IF, THEN, ELSE, REPEAT, FOR, WriteLn). My dad, who taught me programming, suggested I always use variable names in English and comments too. So I did.
Therefore, the idea that anybody would write variable names or comments in any language other than English, even if whoever you work with speaks the same language as you, just feels completely wrong. Mixing English programming language syntax with your native language just seems insane to me. But… apparently it happens. Apparently it happens in huge projects like LibreOffice formerly known as OpenOffice.org, formerly known as StarOffice.
Please don't do this.