Ah didn't know that. Could it be possible to real-time monitor the damage he has taken from each damage type with a damage dumper ? This way, if we can figure out the damage needed to switch shield, we could somehow predict when it's gonna change.
I'm not sure if some damage dumper can already do it. Shouldn't be too difficult to make one simple one that requires you to be in windowed mode so you can see it and that only shows current situation and shows some kind of alert when some set limit is reached. Maybe even writes script in scripts folder that can be called and shown on chat, but not automatically interacting with ao or bot.