shop language miss some translation

My shop is in italian language.
This plugin show italian language, but some words are not translated.
Some example:

– I use min-view and on main page http://www.casabastiano.com/shop/ the word “Size” for each product is not translated.

– In each product details tabs at the end of the page are not completely translated (“Product images” and “Sizes” are not translated, the last one “Mostra descrizione” is translated)

– The word “Back” for navigation is not translate.

What can i do to translate these words?

https://wordpress.org/plugins/wp-spreadplugin/