Hi Philippe,
Thanks for the feedback on the organisation of the new Forum. Feedback is always welcome! Especially now because we’ll have a meeting soon with the maintainers of our website.
It is indeed possible to create topics directly under General, without going to the sub-categories.
So as you are suggesting, creating a topic at the root of General category looks the same as creating a topic under General/Other subcategory.
I don’t know whether it is possible to remove the possibility to create topics at the root of the General category.
It might be easier to close the General/Other category (after migration of the topics under General/Other) than to forbid the creation of topics under General root category, but I might be wrong.