Detecting and adapting to volume isn't that big of a challenge in comparison to natural language processing. But if you mean something more subtle, like discretion or taboo...that's probably much harder than NLP.
Yes, and also adapting to mental concepts of different things.
That starts with phrases, but also applies to other concepts – different cultures have different orientation systems even (some use cardinal directions (north, east, south, west), some use relative directions (front, right, back, left), etc)
Edit: I would highly recommend reading the 2nd paper (which includes some practical experiments testing how Guugu Yithimirr speakers thought about and remembered spatial positions and orientations). It's astonishing.
Even colors depend on cultures heavily. The ancient greek are believed not to have seperated between yellow and green, other cultures similar.
Internationalization is a lot harder than it seems to most people. And then there’s also accessibility.
Even with traditional UIs where everything is hand made it’s already an extremely huge task, but a conversational UI is far more personal.
It has to deal with things like how much privacy or directness is expected in cultures, with taboos, it has to have a full perceptional model of the person who will hear it to be able to properly handle all this.
That starts with phrases, but also applies to other concepts – different cultures have different orientation systems even (some use cardinal directions (north, east, south, west), some use relative directions (front, right, back, left), etc)