HI Gardner Luna,

You are right with:
Your site is multilingual, when creating template style for the language, please assign default language and menu for the template style.
i tickt all needed menu items /template / assignment in -rus -eng template.

But still not showing menu here:
https://www.santegra.de/best/ru/produkty
https://www.santegra.de/best/en/products

Thanks a lot.