I've gotta ask, why blow up their ages like that? I get that they're playing a character but this is absurd.
Flare is an (half)elf so 221 is pretty normal Pekora's ''age'' is likely due to it being easy to remember. She didn't want to use anything near her real age. Rushia's a loli character, so it's due to the ''loli but a xxx years old'' trope
I mean, an average soybean seed (wet) weighs at 120-180 mg. Multiply it by 1000 and you got about 1.8 kilos. Assume it'll weigh less after being roasted, so eating thousands of them most probably actually doable, but not on one sitting. I've seen people downing shelled peanuts like crazy...