Entity without translation
@IgorTengab
An entity in Drupal 8 needs translation to be enabled to be translatable

For example by going to /admin/structure/types/manage/ENTITYNAME > language settings > enable translation

For more info look here

But for your purpose perhaps a light-weight alternative would be to create a custom entity https://www.drupal.org/docs/8/api/entity-api/create-a-custom-content-entity