Thank you for your article.
I just implemented it in my SvelteKit app as described, with EN and DE and without a language switch, but with hooks.server.ts and +layout.ts
When I refresh a page, it shows (correctly) the DE translations for a split second, then it changes to en. I also update the html lang in my hook and notice that it's correct with DE. Therefore something is wrong with the client side. It always changes the locale to EN, no matter what I do. If I call setLocale() in a +page.svelte file manually, it changes to DE but it does not show a single DE translation. Do you have any clue?
Patrick