Hi,
It really depends on what you want to export exactly.
Because you could have an "hard coded" export, where you will export just the columns you want.
Implementing that feature in HikaMarket needs to be flexible according to the vendor rights, so if he does not have access to a field, that field/information should not be exported (and the same for the import).
The HikaShop product export is working good but it export all possible content (categories, product, custom fields... Every available information).
Most of the content is easily available in the HikaShop view "product | export".
The rest is in the "administrator/component/com_hikashop/views/order/view.html.php", for the function "export".
function export(){
$product = hikashop_get('class.product');
$products = JRequest::getVar( 'cid', array(), '', 'array' );
$product->getProducts($products,'object');
$products =& $product->all_products;
/* ... */
Regards,
PS : I'm sorry but HikaMarket 2.3.4 does not exist.