So if staying on 5 mg prenisone is just for mild inflammation that they say is from scarring of the lungs is safe and not harmful , is that true?

It may be the best: That can be done at this time. It is a very low dose so many of the feared side effects are less likely. Also, you need to consider the alternatives and the harm of uncontrolled inflammation. Do give yourself permission to seek other opinions and to ask for even lower or more intermittent doses to be tried while carefully monitoring/measuring the effects. Good luck.

Short term?: Over the short term this is probably not a concern but over long term periods there may be consequences.