Symfony 5, translating database content, who managed to implement it?

Question

symfony

I tried to realize my idea.
Is it worth saying that it didn't work?
Sources.
Translating-database-content
DoctrineBehaviors
The example is outrageously simple.
It works like this

$category = new Category();
        $category->translate("ru")->setName("Вася");
        $category->translate("en")->setName("Vasy");

       $manager->persist($category);
       $category->mergeNewTranslations();

Bands are connected

What is missing to make it work?