The landing page builder hardcodes the lang="en" attribute in the HTML header, even when the site content is manually set to Polish. This is a direct violation of WCAG 2.1 Success Criterion 3.1.1 (Language of Page). Additionally, back-end validation errors (e.g., server-side "Something went wrong" messages) are not exposed in the editor, making them impossible to localize. This creates a fractured and confusing experience for non-English users.