If you give the chess manual during runtime it could work, plenty of examples of that working. If you give the chess manual during training time it wont work, which means that the LLM can't understand what it is trained on. But you could argue that the LLM can understand the data you give it during runtime, it is harder to argue against that, but it is pretty easy to say that it doesn't understand itself ie the data encoded in it.

Maybe you need two models to understand things, since the models wont understand itself but a model can understand the data encoded in the next model. This isn't an unfixable problem, but it is a problem that has to be solved.