Hi Antanana,
The link in the banner leads the user to the translated page into the language the users has set their Mediawiki preference in, it is set to go through Special:MyLanguage. Aka: if you have the language settings (top of your screen) set to Ukranian, you should get the Ukranian banner and the Ukranian language WPWP page as a language page. If you have this set to English, it leads to the English page, and the English version is also the back-up for languages in which the banner and/or landing page is not (yet) translated.
Could you please see what your language settings are currently, and maybe try switching to a different language, refresh your Wikipedia page and click the link again? This should work, I'd love to hear back if it does not, so I can try and fix it!