Another thing is that on the all sharp edges one you may be able to get the fillet to work if you fillet everything instead of trying to leave the knife edge unfilleted. That will make a weird result but you can then extract the fillet surfaces that were created by selecting them and using Ctrl+C to copy them, then undo and then paste them in, and that can give you some rounded section pieces to work with, you would still need to fill in some areas and do some manual trimming to get them into place then.

- Michael