For enabling rollback I always search for roll in both script.rpy and options.rpy as DEV have used one or the other and in some cases they do it in both of them so you have to alter it on both of them. Once you make the change if you are in game you may have to close the game and fire it back up for the changes to take affect or try hitting shift + R to force the game to do a reload. For me I use enable dev mode renpy which has unren built into it. Some DEV's do the rollback limit and set it to 0 and for that you just change the 0 to 100000 or soething.