Search result for other languages go to 404-page

Hi,

1. That's probably because the menu item id that you entered in the menu item option of your HikaShop Products search plugin comes from a menu item which is restricted to only one language. And since you configured the "Force canonical URLs on listings" setting to calculate the URLs dynamically, the system will calculate the URL to the product each time.
The problem is that if the current language and the language of the menu item used by the plugin are not the same, the generated link will be rejected by the SEF system of Joomla when you click on it and you'll get a 404 error.
The solution is to enter the id of a menu item which isn't restricted to one language.
Ideally, instead of translating your menu items by creating different menu items and assigning each to a different language, it's better to setup only one menu item and translate it using Falang or JoomFish.

2. The behavior you're describing when you activate the "Force canonical URLs on listings" indicates that you have a canonical URL configured in your product but that you didn't configure a canonical URL for that product for each language. So the system uses always the same URL, regardless of the language. If you specify a canonical URL for each language with the correct language tag in it, you'll get the correct behavior when you activate the "Force canonical URLs on listings" setting.