How to change all the labels on forms??

Hello,
Pleaes dont take me wrong but, I really dont understand why you dont make easy to find and change the Labels to the forms. (translate them)
I have searched in the /languages/en-gb nothing!
Where are those??
Name, Party, Time, Date, Instructions... fields names??

Hi,
reservation form was built based on plg_gkreservation.zip plugin.
So please find:
administrator\language\en-GB\en-GB.plg_system_gkreservation.ini

Plugin language files are stored always in administrator folder. Why? Ask Joomla Team Developers .