Hi,
The new features of the HikaShop image helper are not yet used everywhere in HikaShop.
We migrate the product page with the new features but not the product listing.
So yes you can add a radius to product images but you will have to override some HikaShop views in order to change the way that the images are displayed and use the new thumbnail function.
Otherwise, if you just want some radius, I think that you can use some CSS. It won't be compatible with all browser (it won't have bad side, the worst case there is not radius on the image) but you can have border radius quite faster.
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.