[Risolto] Problem with xml import in multiligual site

Background of the issue:
I try to add two XMLs with products, one for Greek (default language) and one for English language.
Greek XML: link nascosto
English XML: link nascosto

Symptoms:
When I try to import products in the second language, English product attributes are not matched with Greek attributes, but they are created again. However, products match successfully in two languages because each product's ID is the same in two languages.

Questions:
How can I add English products from XML but ensure English attributes and categories are matched with Greek attributes and categories?