Hi,
Yes, it's possible. When you edit the email, you have three areas:
- the HTML area, that you're talking about with the HTML and the data tags.
- the text area, where you can have a text version of the emails for old email clients (but not really useful anymore)
- the preload area, where the data tags are filled with text coming from the translations or the data of the order.
So in that last area, you can do a lot of things (create new tags, modify the existing ones, etc).
However, if you just want to change the text, I would recommend to actually not edit the email but just use a translation override, like for any text of the interface of HikaShop :
www.hikashop.com/download/languages.html#modify