Does istikhara prevent misfortune, and does the delayed answer to prayer, despite religious commitment, mean a lack of response?

One who seeks guidance from Allah (istikharah) asks Him to choose for them. If a servant performs istikharah while fulfilling the conditions for a prayer to be answered, then only that which is good for them will occur, even if they dislike it, for Allah the Almighty says: "But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah Knows, while you know not."

The believer must be patient and accept Allah's decree, and see mercy in tribulation, for the Prophet, peace and blessings be upon him, said: "Indeed, the greatest reward comes with the greatest trial. And indeed, when Allah loves a people, He afflicts them. So, whoever is content, will have contentment, and whoever is displeased, will have displeasure." It is possible that the istikharah of one who seeks guidance may not be answered if they are afflicted with an impediment to answered prayers, such as heedlessness or doubt.

And whoever Allah wills good for, He inspires them to supplicate and seek His help, for the key to all goodness is supplication and sincere reliance upon Allah. Istikharah is a supplication, and what applies to supplication applies to it.