I don't know if they could be made automatic, but I can think of reasons not to. Namely, Disadvantage is offset by Advantage. So, if you automate one thing that gives Disadvantage you'd have to automate everything to make it accurate. Would make it very difficult and complicated. Edit: Regarding automating it, yes you probably can. The attribute "exhaustion_level" is the number of stages of exhaustion. It should be able to provide a switch to the various rolls to determine if they roll 1d20, or 2d20 keep low.