This thread is resolved. Here is a description of the problem and solution.
I've manually imported the products on the main language, and now I want to import the second using WP ALL import.
Is it Possible?
If you have imported the products manually and not with WP All Import, then the importation of the translated products will not succeed. Meaning that the translated products will not be connected to the original products. You need to import both the original product and the translated products with WP All Import and its add-on WP All Import - WooCommerce Add-On together with WPML All Import.
This is the technical support forum for WPML - the multilingual WordPress plugin.