Does reciting Al-Fatihah aloud in a silent prayer, or not perfecting its recitation due to obsessive whispering, necessitate a prostration of forgetfulness (sujud al-sahw), and does this apply to the last two rak'ahs of a loud prayer?

It is not prescribed to recite aloud in the silent prayer, nor in the last two rak'ahs of 'Isha. If one recites aloud, their prayer is not invalidated, nor is sujood al-sahw (prostration of forgetfulness) required, because performing the prayer silently or audibly is recommended, not obligatory, according to many scholars. It is advised to conquer intrusive thoughts and disregard them by reciting Al-Fatiha with ease and performing the opening takbir without delay.