I have a theory that it should have a very different “personality” (probably more like writing style) depending on language because it’s an entirely different set of training data
In English chatGPT is rather academic and has a recognisable style of writing, if you’ve used it a bit you can usually get hints something was written by it just by reading it.
Does it speak in a similar tone, with similar mannerisms in other languages? (where possible, obviously some things don’t translate)
I don’t know a second language well enough to have natural conversation so I’m unable to test this myself, and may have worded things awkwardly from a lack of understanding
I think the misunderstanding here is in thinking ChatGPT has "languages". It doesn't choose a language. It is always drawing from everything it knows. The 'configuration' hence is the same for all languages, it's just basically an invisible prompt telling it, in plain text, how to communicate.
When you change/add your personalized "Custom Instructions", this is basically the same thing.
I would assume that this invisible context is in English, no matter what. It should make no difference.
I struggle to grasp how that could work though
It's basically just predicting what word should come next, based on many many many examples, but in very few of these examples would a conversation be across multiple languages
Sure it's drawing from all of its training at all times, but that training would inherently be separated
The general explanation at least afaik is that preprompts work because it can predict what instructions would normally prompt people to respond with but there would be few or no examples to draw on of a message being sent in one language and acted on in another