There is no extra meaning in “challenge”. “Вызов” and “испытание” cover the English word “challenge” more or less completely. The problem is that they also accidentally cover the English word “ordeal” as well. Challenge is not something bad or painful, but ordeal is. When you say you want “испытание”, you can potentially be understood as “I want more pain in my life”, which is not what English “I want a challenge” means.
That seems like a bug in English, not in Russian, that you can’t say “испытание” without specifying whether you mean “challenge” or “ordeal”. What if you’re not interested in making that distinction?
There is no extra meaning in “challenge”. “Вызов” and “испытание” cover the English word “challenge” more or less completely. The problem is that they also accidentally cover the English word “ordeal” as well. Challenge is not something bad or painful, but ordeal is. When you say you want “испытание”, you can potentially be understood as “I want more pain in my life”, which is not what English “I want a challenge” means.
That seems like a bug in English, not in Russian, that you can’t say “испытание” without specifying whether you mean “challenge” or “ordeal”. What if you’re not interested in making that distinction?