What would have been a great…
A view under the hood?
What would have been a great addition to this story is a picture under the hood. Several fluid reservoirs, including the wiper fluid are clustered fairly close together. With the current style of plastic covers over everything under the hood, perhaps Hyundai should have concealed things normally not serviceable by the owner.
While a correct action about getting a coolant change, there's no need to freak out the short residence time of a third of a gallon of washer fluid. The fluid, much like the coolant, is mostly water (unlike adding fluid to something oil-based) . The amount of chemicals in relative comparison to the full system capacity is rather dilute. The tank where the fluid was added is largely there for expansion, so what is put in there doesn't necessarily end up immediately circulating through the system.
Get it out ASAP? Yes. But the car isn't going to be irreparably harmed by this mistake, at least not immediately.