If the study result cannot be replicated then the "principles" you refer to are nothing more than superstitions and you can "address them on philosophical level

If the study result cannot be replicated then the "principles" you refer to are nothing more than superstitions and you can "address them on philosophical level" all you want, that won't make them any more true. The fact that those things (like challenging yourself, seeking novelty, etc.) are often quoted in context of IQ increase just comes from observing the behaviour of highly intelligent people and then confusing the cause with effect.