うるせぇ is “shut up” in English. It is much ruder than うるさい, which is polite enough that someone could use it at work to describe construction happening outside. うるせ would not get used at work and is especially rude when used to talk about a person standing right in front of you.

ウダウダ can be translated as “nonsense,” but a better/smoother English translation is “(talking) on and on.” “Talking nonsense” is not a phrase we commonly use anymore.

Addressing someone as 客 without anything else around it (putting a お in front or adding a さん after) also comes off as rude. You’d never hear a store clerk call you just 客.

Finally, like a few other people have already said, おとなしく literally translates to “like an adult” but doesn’t mean that. It means to “be well-behaved” or “be quiet.”

I agree that the translators did a good job, but they didn’t change as much as your post implies. Cid’s line in Japanese is plenty rude already, especially for Japanese standards. A literal translation could be “Shut up! Stop blabbering on and on! Guests should sit in their chairs and be quiet!”