Is it permissible to adopt the view of one who does not deem the Fatiha obligatory for an individual in order to repel misgivings (waswasa), and does intentional mispronunciation in the Fatiha invalidate the prayer according to those who hold it to be Sunnah?

The statement that Al-Fatiha is sunnah (definition) for one praying alone is not authoritative in the four madhhabs. Rather, it is a pillar according to the majority or obligatory according to the Hanafis. It also contradicts the hadith (definition): "There is no prayer for one who does not recite the Opening of the Book (Al-Fatiha)." The person afflicted with obsessive doubts (waswas) does not need to seek a dispensation with this statement. Instead, they should ignore the whispers of waswas, recite Al-Fatiha normally, and pay no attention to the doubts about mispronunciation; by doing so, they will get rid of the waswas. The question of intentionally mispronouncing is from waswas, and a Muslim should pray in a normal way, with ease and simplicity.