Does multi-course search take into account a user with different roles in different courses?

Review how Atomic Search takes user roles into account when showing search results.

Does multi-course search take into account a user with different roles in different courses?

Yes. If you are a teacher in one course and a student in another course when you do a multi-course search, results from the course you are a student in will only include published items; results from the course you are a teacher in will include published and unpublished items.