I’m currently working on translating our website into French and I encountered some difficulties when creating blog posts in a different section than the original one. It works in the webflow preview, but it shows a broken link when trying to access.
Thanks for posting! I took a closer look at your project and it looks like there’s not content on the fr-blog/ pages.
If there are no elements on a template page, it will show as a 404 error on the live site. As soon as you add content to the template pages, though, you should be able to publish and see these pages as expected.