Of those 300, roughly 50 are concerned with medical complications.
That's true, and I wouldn't want to deny complications exist.
That said, I don't think the existence of complications is sufficient in-itself for classifying a procedure as dangerous.
In the words of the study's background:
"Surgical treatment is
effective for obtaining male-type chest walls, which are their original shapes,
reducing mental stress and increasing sexual happiness. For male type thoracoplasty for trans men,
it is safe to obtain good results by determining the surgical method using an algorithm depending on the morphology of the breast. However, it is also clear that various complications occur at a certain rate."
So the study summary you selected argues that it's effective and determining the surgical method using their algorithm is generally safe.
For some reason, I expect you to ignore both of those facts to use the complication only to suit an argument the summary does not align with.