So sorry for your loss. End-of-life decisions are inherently fraught; no matter what you do, you will likely second-guess yourself. I just let an old hen die naturally (heart failure) because she did not seem to be in pain or distress and still wanted to be with the flock as she could. But she...
Love that you do what you can to give hens with salpingitis a reasonably comfortable life for as long as possible. You are paying attention to them and doing what you can for each individual.