Yes, I confirm this solution posted by ToroLuke on January 29, 2014 ("Apply language settings to the welcome screen, system accounts and new user accounts" and then "Copy settings"). It has been working for me too. I have turned off and on my laptop about three to four times and my language settings are still there.
Thank you for posting and sharing this solution, ToroLuke. After almost two years there is finally a real solution and you found it.
You are the man!