Problem in Greek language

Hello,
I inslall your plugin and it looks great but there is a problem that there is not a translasion in Greek language the “Order date” label, all the invoice table headings and the labels “Subtotal” , “Fee” and “Total”.
The label “Order date” and all heading labels are looking OK inside the plugin in Greek language.

Also is there a way to remove the “fee” label?

Thank you in advance for your help.
Regards
Nassos