For logins, we're already used to the fact that they're expected to be in Latin. Having them in the native alphabet is more trouble than it's worth (one system supports it, another breaks etc., easier to remember one, in Latin, across systems) I'd be irritated though if I couldn't use my native alphabet in the user profile for the first name/last name
>Please provide your name exactly as it is in your government documents.
>This is extremely important. Failure to comply will lead to termination of your service with no refund, criminal prosecution, our CEO calling you in tears and a hitman being informed about your last known location
...
Validation error: "First name" contains invalid characters.