Bilingual web – opposite item in menu. How?

Hi, I need really simple behavior and I thought this would be like basic item in the new menu items next to “Current Language”.

I have web with only two languages (English and Czech -default). I need to have in my main menu item “English” when the Czech is active and when user click on “English”, the menu should show “Czech” (when english is active).

I tried this: https://translatepress.com/docs/developers/show-opposite-flag-menu/ but it does nothing and it is for flags..

Can you help me with this? ?? Thank you so much!

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