Hello,
Your page "download your gift card" is not related to HikaSerial ; it seems to be the HikaShop download listing page (feature of commercial edition of HikaShop).
Regarding the "download gift card" in your order details ; it should display the filename that you have specified in your product configuration.
You can edit your product files to change the name of it (and it's still related to HikaShop and not HikaSerial).
Afterwards, please note that you can override every HikaShop (and HikaSerial) translations :
www.hikashop.com/download/languages.html#modify
If you have any further question ; please open a new thread in the HikaShop section of the forum since there is currently not direct relation with HikaSerial feature in your current message.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.