It will automatically target low HP members and it will take into consideration proximity for what spell it casts. So if you’re not in range of a lot of people it (in case of WHM) it will prioritize Cure healing, if close Medica, if really close Cure 3.
Same with stuff like Benediction, it will pop a full heal on someone that’s dangerously low, unless you have enough oGCDs to get them back up comfortably without much DPS loss.
It’s actually a very competent bot, save for as I said, Lv80 rotations. (You will need to effectively pop Temperance yourself for mitigation and help in heals at the right time, the bot won’t do it for you)