>>5569
Partly right, but mouth is: 口 (くち, コウ, ク)
Pretty sure shiran is an informal shiranai. So that's the "doesn't know" part. I don't know jej how that fits in with the rest of the rest of the sentence, but maybe it's a double negative thing. "She doesn't know how not to listen with her mouth?"
I actually see where the translator got the "adult" part, from 方
Only thing is my dictionary says has kikikata as 聞き方 (ききかた): way of listening, listener.
I assume that's the correct reading, cause it makes more sense.
koitsu is kinda like "this dude." Jumbo has a particular way of talking. Not sure if it's inherently masculine, but he's the type that would address yotsuba as dude.