Roan was thinking about the Jade Slip the twins got back in the Jiran Forest. They didn't dare to enter it in the past because it had Stage Four Demon Beasts. In fact, even now, entering it at their level was not a good idea at all. Not to mention that Juri said that there were rumors of even Stage Five Deamon Beasts existing in there.
However, Rean and Roan were planning to enter the Core Formation Realm pretty soon. Once they do that and put all their abilities together, their average strength should shoot up significantly. With Rean's Enhancement and Roan's Shadow Steps, they should at least be able to escape if necessary. Of course, that was only in the case of Stage Four Demon Beasts. If a Stage Five Beast appeared, the story would undoubtedly change.