Hello,
By using the "email" button in the toolbar while you edit an order in the HikaShop backend, you will be able to send test emails.
Each time "attach serial" will perform his task and generate the image.
One other solution is to configure "attach serial" to work as virtual download file and set a product file to your test product.
Afterwards in the backend you will just have to download the product file to get the new image.
If you have product custom fields, you can access them thanks to "product..." and specifying the custom field namekey.
The plugin will get the content directly from the database.
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.