Thats just not what a segmented run is. Just like any game that allows save-states, you could abuse save states to retry any part of 'the run' changing the entire save file to a different run and 'splicing' them together is splicing, which is not allowed. Tweaking fireball damage is literally hacking the game to get the desired result. Unless you find a way to perform ACE with your inputs. Which is not the case here.