Problem with trailing slash and global redirect
if you are looking to redirect your users site or visitors to the right language you can do this without global redirect module 
to do that


install [Localization update][1] , [variable][2] , [Internationalization],
after install modules active Locale , Localization update , Internationalization , Variable 
go to Configuration > Languages > detection and selection 
the 1st option URL u can choose between (Path prefix or domain)
the 2nd option is Browser and here u can Determine the language from the browser's language settings. if your browser's visitor is English he will go to English site .... 
the 3rd option is User in this option the site Follow the user's language preference.


that's all