Hi,
First, you need to clear these automatically generated URLs with a mass action with an action "update the values" on the "product_canonical" field with an empty value.
Then, you need to understand how the "Use canonical URL and generate it if missing" setting works. When HikaShop has to display a product in a listing with that setting, if there is a canonical URL provided in a product, it will use it, otherwise it will generate it as if it was dynamically generating the URL.
The URL /somethingdifferent_ch/index.php/hikashop-menu-for-products-listing/prod/funky-blender-raspberry-cherry-heritage-4-cherry-blend-5-5-20 indicates that the product was displayed in a listing from the "hikashop-menu-for-products-listing" menu item, or in a module with that menu item selected under the "menu" setting of the module.
So supposing you don't have modules wrongly configured which display on the main products listing menu item you want to use for the URLs, you could just browse your main products listing menu item listing pages after the canonical URLs have been emptied and it would regenerate them the way you want.
An alternative would be to use a mass action with an action "update the values", but instead of using the "string" mode with an empty value to erase the canonical URL, you could use the "operation" mode with a value like this:
biere/{product.product_alias}
This however supposes that your products alias is properly configured with the alias you want to be used in the URLs and not generated from the product name. So this might not be practical.
You can read more about mass actions here:
www.hikashop.com/support/documentation/167-massaction-form.html