A comment above this talked about this topic and that it was somewhat reasonable that the people did such a thing. "Their lack of food knowledge is not that unrealistic. Their society is relatively conservative, which may make them reluctant to explore, and their country is known to have a high food culture, which make them take great pride in their current recipes. Burned fish is sophisticated food in their opinion, and it only becomes disgusting when compared to better food." That's what they said.
the only problem is that they have taste buds,
Why would they say risa's cooking is delicious?
Why would they even think of accepting Risa's cooking if they think their cooking is better?
I still think the author should've made the kingdom some sort of strict spartan nation ta make it even a tiny bit believable.

Wtf were they learning from?
Caveman teacher?
Where are they getting pride from?
They don't have taste buds and dare call themselves chef by sticking to stupid traditions?
Are the people here retarded?
I would have believed this story if they were shown just eating everything raw!!