"I do not like people who happily talk about other people's ugliness " should be accepted, right?
Very clumsy english translation. Better: "I do not like people that are happy talking bad about others. "
Your translation isn’t grammatically correct. Bad isn’t an adverb. Poorly, maybe. Maybe that’s just a feature of The English you know, but in Australian Standard English your sentence is incorrect.
Where is "other" here?
other = lain
Of course it is! Thank you.