Your therapist can't diagnose people you talk about in session, including confirming armchair diagnoses that you made.
Any commentary they make in response to you raising the issue of someone else's diagnoses should be something to the effect of "it's possible that they have x disorder, but it's more important to focus on how their behavior affects you / the relationship."
If your therapist says "you parents are narcissists" or "your ex is a sociopath," that either didn't happen, or they're creating an ethical violation.
They aren't allowed to diagnose someone who isn't their client, i.e. has consented to treatment.
Even if they were allowed to do that, your secondhand account of that person doesn't constitute an assessment.
Even if they were allowed to do that and could use your secondhand account, they wouldn't be able to tell you about someone else's diagnoses because of confidentiality.
Further, your therapist can't diagnose you with "narcissistic abuse syndrome" etc. because it doesn't exist. There are no legitimate diagnoses based on the (speculative!!!) diagnoses of an abuser; you're likely talking about complex PTSD, which commonly results from abuse (including emotional abuse).
I don't trust therapists who slap diagnoses on their clients' abusers. You shouldn't either. You should know the basics of clinical boundaries and the correct terms for things so that you don't feed into stigma or put up with a therapist who's willing to engage in unethical practice.
If they're focused on diagnosing your abuser, they've got blinders on and won't be able to objectively evaluate your situation to help you heal. Ultimately, telling someone that their abuser is a special type of person and they have a special type of trauma rather than focusing on behavior, impact, and symptoms isn't good therapy and it won't help you heal.
