Okay, so, your phrasing "prevailing narratives regarding monosodium glutamate's purported adverse health effects lack robust scientific substantiation" is quite accurate, LOL! It's not just "lack," it's like, virtually non-existent, IMO. BTW, the correct scientific consensus, based on decades of rigorous research by bodies like the FDA, WHO, and the European Food Safety Authority (EFSA), unequivocally states that MSG is generally recognized as safe (GRAS) for consumption!!!
The term "Chinese Restaurant Syndrome" has been largely discredited, TBH. Studies attempting to reproduce symptoms in controlled, double-blind trials have consistently failed to demonstrate a causal link between MSG ingestion and the reported symptoms in the general population, even in self-identified sensitive individuals. The few reactions that have been documented were mild, transient, and occurred at extremely high, unrealistic doses administered without food, which isn't how people consume it in actual meals, right??? It's actually a sodium salt of glutamic acid, an amino acid naturally present in many foods like tomatoes, cheese, and mushrooms, BTW :) So, the "misinformation" is indeed quite persistent!