Reign of Terror mod "to-do" list (click to expand) (Cloud saves enabled): Steam\userdata\random numbers\219990\remote\save\user\ _CHARACTERNAME\maps_world.map\DIFFICULTY (Cloud saves disabled): Documents\My Games\Grim Dawn\save\user\ _CHARACTERNAME\maps_world.map\DIFFICULTY All you have to do is copy over the quests.gdd and conversations.gdd files to the character save folder in whatever difficulty you need and it sets your character’s quest objective to that point.
Make sure to start RoT as the first game mode if you decide to play it.