Hi @Unai,
Jumping in here to share with you what tech experts explained. Check this post from Pat.
Specifically, that you can’t link through multi-entity fields to get a specific result:
You should know, however, that you can’t use linked filter syntax in a field list if one of the links in your path is a multi-entity link. By definition, a multi-entity link you hop through would have to follow multiple paths and there’s currently no way to reflect that in a result set.
For example, in the following, it would be impossible to flow through all tasks to return multiple statuses:
shots = sg.find('Shot', [['id', 'is', 1234]], ['tasks.Task.sg_status_list'])