I can't think of any harm from doing a slow taper. But it seems there is harm in doing a fast taper for you!

My very elderly mother stayed on 2mg for a long time after getting down from 5mg. Eventually she went to 1mg. At that level it isn't affecting the immune system as you know.

In our experience (my family's) the tapers get harder as you get to the lower doses. With some meds we have used liquids or had something compounded so very small doses could be taken.

I don't see how you could evaluate what else is going on until fully off the prednisone.