As far as I know, Mado dying IS the popular opinion. The idea that the jellies were aesthetic/a symbol is quite recent and not well established or anything.>>8819
To be fair, there's a great amount of japanese symbology and mythology in the game that points out she knows too much about it (zukin ghosts (kerchief-over-head ghosts), oni, nopperabou, yuki-onna, etc), just as there's south american symbolism. Ignoring this and saying "there's no evidence" would also invalidate your own point as there's no direct evidence she is south american except for that symbolism.
Do note I'm not denying or asserting either.