Would it be possible to somehow have a flag on a Trigger that would prevent it (and everything triggered by it) from being undone? Or a key command trait you could add at the end of a Trigger sequence that would serve the same function?
So many varieties of bugs seem to occur with undo, and if you know undo can or will break something, it would be nice to be able to put in a simple measure to prevent players from breaking things. I suppose there might also be a case for preventing undo of randomisation events and information reveals for some modules.