> (This difference possibly shows the more fundamental difference in the cultures, where one values truth more, and one values agreement/harmony more.)
I'd be extremely wary of ascribing any cultural significance to the language modes here. Negation and especially affirmative/negative responses to negative questions is just extremely variable among languages. Even languages in the same language family just end up doing it differently.
Even more confusingly, in casual speech I'd probably respond to that question in English like, "yeah, no I didn't go" or conversely "no, yeah I did end up going"
“You didn’t go?” → “No, I didn’t go” (agreeing) or “Yes, I went” (disagreeing).
In Japanese, you should say “yes, I didn’t go” or “yes, I didn’t go”:
行かなかったんですか。→ はい、行きませんでした。(agreeing with the negative) or いいえ、行きました。(disagreeing with the negative)
(This difference possibly shows the more fundamental difference in the cultures, where one values truth more, and one values agreement/harmony more.)
I’m not saying that’s what happened to you, just that it wouldn’t necessarily be wrong to see it.