The confounds that you describe are important ones, but it strikes me that even the Iraq pre/post-deployment study (from the abstract; I don't have access to the text) doesn't seem to have any metric for growth aside from presence of symptoms.

Is there any reason to believe that both things could not be true? That is, could people both have grown in some meaningful sense but not in the sense that they are not still impacted by previous trauma?

For instance, if I responded to a traumatic event by arguing less on the internet, spending more time with my children, and taking long walks in the forest while appreciating the beauty of nature and reflecting on how my daily actions contribute to the preservation of the planet, one might say, in some sense, that I have "grown"--but I might still suffer considerably from the psychological impact of the trauma itself. Furthermore, even if I am still suffering from the original trauma, I might be more resilient to other hardships that are not direct triggers of the trauma (e.g. I might better handle a financial stress even if I have not fully recovered from a violence-based trauma). Blackie et al. 2017 is a start, but is underpowered, has rather dissimilar control and recent-adversity groups, spans a relatively narrow time window and is not longitudinal, and consists entirely of college students. As a hint, as a step on the way forward, this is valuable, but it is far from what would be needed to make sweeping generalizations.

So it seems that to answer the question about personal growth in a comprehensive way, one would need credible independent metrics of personal growth, and it doesn't seem that those exist in well-validated form. Of course, even if the accounts of personal growth turn out to be objectively validatable in many cases, it does not mean that the people would not also benefit from improved support for recovering from trauma: again, personal growth and continuing trauma are not necessarily opposites.