E-mail Templates options screen: Show first & last name shortcodes

[naokomc]

Show [last_name] and [first_name] in addition to [buyer_full_name] to accomodate for languages with family name -> given name order.

[buyer_full_name] isn't ideal for languages like Japanese, Chinese, Korean, and Vietnamese where the family name is placed in front of the given name.

@mayukojpn pointed out that [last_name] and [first_name] should also work. We tested this and it worked fine.

Why not expose last & first name options on Tickets > Set up > E-mail Templates page?

[coreymckrill]

Thanks @naokomc!