Il est vrai que, malheureusement, la gestion complète des catégories ne peut pas être totalement déléguée.
Peut-être que le document suivant peut t'aider et notamment le partial workaround proposé :
Creating a new role with a single capability allowed - moodle/category:update - and assigning the user to this at the site level gives them access the category and course editing screen (or it should). They will *also* be assigned to the administrator (or equivalent) role in the appropriate category context.
This gives them access to the course/index.php screen enabling them to manipulate categories. The roles system (mostly) controls the rights appropriately to the category editing functions.