Hi @dotancohen
After you set the values of the custom fields, you will see the custom fields’ name listed under the Multilingual Content Setup. From that options, you can set the custom fields to copy so it will use the master page’s values instead. Please take a look at point number 4 on this page: https://www.advancedcustomfields.com/resources/multilingual-custom-fields/.
I hope this helps 🙂
