How to modify the language and check out fields

Is there really no way of changing the plugin′s language? I have translated manually all that can be changed through settings but there are still tons of little messages that cannot be changed and remain in english.

Likewise, I can′t find a way to change how the [cart_submit_form] short code behaves. I just want to get rid of some unnecessary fields (postal code, country) and change some that are required to optional (phone number, email, address).

Thanks for any help.