Thanks for reply Encho 
We tried to print the error message receiving on logon screen and could see error.getMessage() method returning property's field say for password has expired error message, it shows "PASSWORD_EXPIRED", and same for others except one i.e "Invalid new password must be no more than 7 characters long", it seems for this error, its property and value has been set to same..that is the reason we are not getting the translation...could you pl let me know where could we see this or do we need to raise ticket??
BR,Tia