Steps to reproduce

1. Install Ibexa DXP
2. Edit Landing Page content type and unselect Translatable option for landing page field
3. Create a new language
4. Start to translate landing page content

Result

The landing page can be modified, you can edit/add/remove any block. Saving/Publishing the content means that all changes will not be saved/published

Expected

The landing page should have information like other fields that it is not translatable and that no modifications can be made