But saying unko wouldn't get a kid punished like that because it's not as bad a word in Japanese. Kuso would be closer in meaning to the expletive. Since they're both adults both poop and shit are fine translations. Only the context would effect which is used.
Wordhippo is a good thesaurus but because it gives you so many examples of the same phrase or word, it's not good to use as a translator. You need context.