Based on your description, it seems that you have skipped a step ( Enable languages for your website in the Portals Management app)
and tried to add localized content without enabling the languages for your website. This could cause the issue you are facing, as the website does not recognize the language of your content page.
To fix this, you need to go to the Portals Management app, select your website, and add the languages you want to support in the Supported Languages section. Then, you can assign your content page to the website and the parent page, and it should show up on your website.