This is based on the assumption that a user writes and understands English absolutely well. However, they will write their work in another language other than English.
So does Scrivener work for them in these 3 scenarios?
Novel
Non-fiction work
Screenwriting
In my imagination, it seems that Scrivener will still work well if you write a novel or a non-fiction work.
But how about screenwriting and its formatting requirements? Will Scrivener work?
The Scrivener editor is language-agnostic. Text is text, no matter what language you use.
As you are fluent in English, you may prefer to use the English interface, since that will match the documentation and will not be subject to inconsistencies that can occur with the translated interfaces. Similarly, since we rely on third-party spelling dictionaries, you may find that some languages are handled better than others.
The Compile formats supplied with Scrivener use English for things like chapter and part headings (Chapter One, Part Three, and so on). You’ll want to familiarize yourself with the instructions for editing these elements as needed for your target language.
For screenwriting specifically, you will probably want to edit the Script settings to match the requirements of your target market, and to change terms like “Fade In” or “Interior” to whatever is appropriate in your target language.