Hi,
For your questions or feature requests related on HikaMarket ; the best is to use the HikaMarket forum section.
I have added your request in the HikaMarket TODO list ; like you noticed, it would require a modification in the HikaShop shipping list in order to let external plugins (or add-on) to dynamically add columns in the listing.
Then, HikaMarket will be able to use the trigger to add his specific content.
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.