This is an interesting question because wisdom is trait that we need to infer from what Jonas does and says rather than being a characteristic that is directly applied to his person. To answer this question we need therefore to analyse what he says, does and thinks, and find an incident where he demonstrates wisdom. For me, I think we can find such an incident in Chapter Seventeen, when Jonas tries to explain to Asher that the game they are playing actually came from wars that were fought long ago through suffering. Although he tries initially to explain to Asher what is bothering him, at the same time he shows wisdom is recognising that he is not able to do so, even though this leaves him feeling intensely sad and depressed:
Jonas trudged to the bench beside the Storehouse and sat down, overwhelmed by feelings of loss. His childhood, his friendships, his carefree sense of security--all of these things seemed to be slipping away. With his new, heightened feelings, he was overwhelmed by sadness at the way the others had laughed and shouted, playing at war. But he knew that they could not understand why, without the memories.
Jonas thus shows wisdom in identifying the changes that have happened to him and the very person that he is now, and the way that this has created a division between him and his friends, but also the way that he cannot attempt to try and mend this division. He recognises the futility of trying to explain.