When you say "fixed", I assume you mean that the traumatized brain is returned to a state where a person can learn and experience positive emotions. In most cases, I would argue that it's probable, yes, but I'm not an expert in this area, though I spend a lot of time trying to understand abuse (to remove it from my own language and actions) and trauma (so that I can help my children recover from it).

It is my very slightly educated opinion that given a place of psychological, emotional, and physical safety, it is possible to train a person to gain resilience. I will also say that places that meet these criteria are rare in the United States, at a minimum. Our society is highly competitive and attacks people who do poorly, even though that's largely assigned at random, or is based on already existing/trained resilience, which is not well taught in most schools in the US, at least not to the extent that it needs to be. Emotional intelligence is the primary toolkit for dealing with these kinds of issues, and it can't just be taught as a one-and-done. It is something that requires constant practice, similar to sports or music preparation.

I would even go as far as to suggest that the entire media system, for all that it does well, strongly encourages reductions in emotional intelligence. Advertising is designed to get us to relate to emotions like pride (buy a brand new vehicle to be your own person!) or fear. Facebook pushes anger at us regularly. The fundamental attribution error is so rife and abusive in our society that now we identify ourselves almost completely via the categories and labels that are tossed around so lazily, inducing category error, outgroup bias, and a whole slew of cognitive errors that reduce emotional regulation and empathy, key tools in maintaining a healthy mental state.

Given all this working against us, on the other side there needs to be understanding that safety isn't enough. Abusive language is incredibly common in the US (I don't have insight to what the media really looks like in most of Europe, or Asia). There are positive actions that can be taken to help people around you to heal, and to heal your own mind if you are concerned about hieghtened anxiety or depression, but they probably require counseling (hard to access and expensive), meditation and or pharmacology.

I would recommend understanding NVC (Non-violent communication) as a strictly non-abusive method of communicating with others, understanding abusive language patterns (name-calling, dismissing, condescension, etc.) which are easily found online, and also reading books like "Trauma and young children: Teaching Strategies to support and empower" by the NAEYC. The understanding of trauma, how subjective it is, and how often it is associated with thinking patterns and how to modify them, is key in helping people recover from trauma.

As a side note: I have had to do a lot of counseling because the 750k dead in the US from Covid caused me a lot of secondary trauma. I have a tendency to think in the empathetic, and updating from empathy to compassion freed up a lot of room for new ways of thinking. However, I have access to the necessary health care. People who are under intense pressure (month-to-month pay, homelessness, bullying, etc.) will not be experiencing what is called "toxic stress", which alters the brain and practically eliminates the ability to build good connections in the prefrontal cortex.

I guess what I'm saying is it can be done, if we reorganize society for mental health, or if you have the money.