A question about language

I have made a installer for multi-language using modern UI style. I wanna use the system language, so I hide the language-choice menu. But yesterday, after I had added a command "RequestExecutionLevel admin" and compiled it with the newest version of NSIS, it no longer showed the system core language but the UI language instead. I wonder which had cause the change, the command or the new version? Does anyone have any idea?

The new version. From the release notes of 2.13:

Language detection has changed. The default language is now set to the user's user-interface language instead of the locale language, as suggested by MSDN. To restore the old behavior, use System::Call "kernel32::GetUserDefaultLangID()i.a" in .onInit.