Is facing problems after the الاستخارة prayer considered an indication of the الاستخارة's validity?

If you seek Allah's guidance (Istikhara) in a lawful manner and feel a sense of relief and openness in your heart towards a certain matter, then you will only encounter good. The problem you have fallen into may be a divine decree (Qada' wa Qadar (definition)) from Allah Almighty. Perhaps Allah averted a greater calamity from you, or it was a means for you to feel your need for Him, and the sorrow that befell you expiates your sins. Therefore, you must fear Allah (have Taqwa (definition)), supplicate frequently, and seek forgiveness (Istighfar).