If you use the free GTranslate plugin, the language your visitors choose does not carry into the HomeRunner booking flow.
Why this happens. The free GTranslate plugin translates in the browser using a Google Translate widget. It does not change the page URL and provides no search-engine indexing. HomeRunner’s multilingual support keys off the language code in the URL path (for example /nl/ or /fr/) or the header that GTranslate’s paid service sends. The free plugin provides neither, so the booking flow does not receive the language.
What you can do. For the booking flow to receive the correct language, you need a paid GTranslate plan with sub-directory or sub-domain URLs.