Mantras are only endowed with transformative electric power if specified in initiation (dīkṣa) from the mouth of the Expert. It's not necessarily much appropriate pronunciation, but rather the ability with which the mantra is endowed that gives it reworking functionality. Vishishtadvaita Vishishtadvaita is one of the main branches of Vedanta, https://www.youtube.com/@Mahavidyabaglamukhi/