In WordPress, since few version there is a setting in each user profile to select a language which have higher priority than site language. This can be the answer of the back office always in Hungarian.
About WooCommerce emails, they are sent in the default website language unless a custom code or a plugin come & change this behaviour.
Unfortunately, without more information, we can’t help you more. Maybe you can copy & paste your site health report here? (wp-admin / tools / site health / Tab info and then click on “copy site info to clipboard” button.
Thank you