This is expected since your IP address and geolocation are changed to appear as if you're in the country that our server is located in. It means that Proton VPN is working as intended. Whatever server you connect to, you're likely to be served content in the language of that server's country.

That said, the default Connect option will connect you to the fastest available server for you. This leads to better load balancing and higher speed, which is a priority for free users. You still have the option to switch to another randomly allocated server, or you can upgrade to connect to a specific server in a country of your choice.