Multilingual WordPress SEO architecture after an AI site migration

Why multilingual sites fail silently

Many AI-built sites switch language with JavaScript after the page has loaded. The server sends the same English HTML for every language address, and only the browser swaps the text. To a crawler that first reads raw HTML, all those addresses look like duplicates of one page. The result is that translated pages are grouped together and only one version is shown in search.

WordPress solves this structurally when it is configured well: every language version is a separate page with its own server-rendered content.

The four signals every language page needs

First, the html element must carry the correct lang attribute, and dir="rtl" for Arabic, Hebrew, Persian and Urdu. Second, each page needs a self-referencing canonical with an absolute URL. Third, every page must list all its language alternatives with hreflang, including itself and an x-default. Fourth, the title and meta description must be translated, not just the body text.

These signals must be present in the initial HTML response. If they only appear after JavaScript runs, they are not reliable.

Choosing a URL structure

Subdirectories such as /nl/ and /de/ are the simplest and keep all authority on one domain. Subdomains and separate country domains are possible but require more maintenance. Whatever you choose, keep it consistent and make sure your sitemap lists exactly the URLs that exist, with matching hreflang annotations.

Translation quality and depth

Search engines evaluate each language version on its own merit. Machine output that leaves English fragments, broken links or untranslated headings weakens the whole set. Review each language as a native reader would: headings, buttons, FAQ answers and closing paragraphs should all be in the target language. Quality across fewer languages beats thin coverage of many.

Redirects and lost URLs

During a migration some addresses inevitably change. Every old or unknown URL should return a permanent 301 redirect to the most relevant live page instead of a 404. This keeps external links valuable and gives visitors a working page. Avoid redirect chains and never redirect back and forth between domains.

Monitoring after launch

Submit one sitemap on the exact host you use, for example the www version. Use URL inspection to test a few language pages live and confirm the canonical Google selects matches yours. Expect rankings to fluctuate for a few weeks after large changes; that is normal while the new structure is processed.