Was going to say exactly this.
I’ve had several periods in my life where I have unsettling dreams and nightmares. Every time this has occurred to a distressing degree, I have always found it correlated with something happening in waking life.
Dreams can be reflections of waking life and mindset or mental state. To work through my stressful dreams it’s helpful for me to interpret them and find what insight they might provide on my waking life situation or what they might say about where my stress is coming from. In this way my dreams inform me for what actions I might explore in waking life.
I have not really found lucidity to be a cure for nightmares, but it can be a helpful tool.
Unless you end up being a really sharp lucid dreamer that can turn every single nightmare around, dream control based solutions ends up being more sporadic symptom treatment opposed to treating the cause, which is likely in waking life. (note: lucidity does not equal dream control).
At worst, using lucidity to try and manage my stress dreams made me very paranoid and feeling more helpless in the case that I wasn’t able to change my dreams even with lucidity. At best (and this would be what I recommend if you do decide to use lucidity) I use the autonomy lucidity gives me to explore possible solutions and interact with my challenges instead of pushing them away with dream control.
The things you listed that you’re doing sound like a good start to me. I would encourage personal dream interpretation where you try to find interpretations that resonate with what they’re going through or what symbols may have personal meaning. I discourage dream dictionaries for interpretation as they can’t know your personal experience.
Even if they do not want to lucid dream, I think you could adapt some lucid techniques that could help, such as dream incubation and MILD mantras!
Dream incubation can be planning a specific dream or focusing on a specific topic to dream about. This can be used to shift their focus from nightmares and suggest calmer dreams to themselves OR, they can focus on whatever the waking life problem may be (if there is one) with the incubation that dreams may provide some solutions. I’m not sure if I’ve really ever seen a clear tutorial or suggestions on how to dream incubate, you might do some more research on this.
I can share how I do it though. (click for this section to expand it and see it)
First: I identify what topic I would like to dream about. I write it down. If planning a specific dream it could be scripted, (but I don’t do this because I don’t like to direct the outcome that much because it leaves less room for subconscious insight and such.) For your friend it might be something like: “Incubation: relaxing on a beach.”
Let’s keep using that as an example.
Second: I actually write down why I want to have a certain dream, in this example it might be “I would like to experience a calm dream.”
Third: I will write down the emotions I would associate with this dream and try to feel them as I do this. “Associated emotions: calm, relaxed, safe, at peace…” etc.
Fourth: I write a “how” section, which includes potential manifestations of the incubation. For the example I’ve provided, it may be a little redundant with the goal: “How: dream I’m walking on a beach, dream of laying on the beach, etc.” (when the goal is more about problem solving, this section may be more relevant as it’s a little broader than the example. Like if my goal were to “process being attacked by a dog,” this section may include: “visit the location I was attacked, interact with the DC representing the people that helped me when I was attacked, interact with DCs representing the people who have hurt me while seeking support, relive the memory but with a different outcome to see how that would have felt, etc)”
Fifth: I make a MILD mantra or two to use based on this incubation I’ll cover this outside this section as it can also be used on its own, but I find the structure of things before this helpful. For the beach example it might be “I dream of walking on a calm beach,” “I will write down my calm beach dream in the morning.”
Sixth: This one is more optional and sometimes irrelevant, and sometimes I do it earlier in the process, but I’ll list any facts associated with the incubation topic or questions I’m exploring regarding the incubation topic. The beach example probably doesn’t work here (but for the dog example, I might list things like the facts of what happened, or questions I experience or would want answered by my dreams “why did I respond this way?” “what could have happened if I did something differently?”)
Seventh: I review the incubation when I finish all this, and kind of try to pull it all together in my mind and tie it to the mantra. I will envision the various manifestations I’ve suggested of the incubation while repeating the mantra and focusing on the associated emotions.
I try to revisit the mantra and incubation throughout the day and with extra focus before bed until it manifests.
MILD is a popular lucid dreaming technique (and my favorite). It’s basically setting your intention to remember to realize you’re dreaming, and this is often achieved by using autosuggestions/ mantras (like “I will realize I’m dreaming”). However, MILD mantras can also be used to achieve other dream goals like improving dream recall and help manifest incubations. (“I remember my dreams,” “I will fly in my dreams.”)
I really recommend this post and (lower down on the same thread) this post for helping create a meaningful and useful mantra. You can craft a mantra for calm dreams or for a specific calm dream scenario (discussed as incubation). This may be a nice addition to self-soothing and relaxation to focus on calm emotions you may like to associate with the mantra.
Note: With both incubation and mantras, I try to focus on only one topic at a time (with the mantra relating to the incubation.) Sometimes I use more than one mantra, but it’s usually just a rephrasing of the original mantra to give my brain some different words options to process.
These things can take time to take hold and manifest, but you may be surprised the ability we have to influence our dreams like this. If dreams are reflections, then incubations and mantras give yourself material to be reflected in your dreams.
The good news is that these methods are things you can do in waking life and without lucidity!
Hope this is helpful.
The only other suggestion I could think of might be professional counseling if they are indeed going through something.