No, currently unicode characters for non English languages does not supported in data export from table or datatable.
In Smart School avoid to enter or using special character (special character is non-alphabetic and non-numeric like @, #, $, <, %, ^, &, *, !) for any field like Student, Staff, Income, Expense, Transport, Custom Field etc, otherwise it may fail PHP or JavaScript processing.
Your getting this message because Mod_Security is preventing download of sql file on your hosting server so you should disable Mod_Security on your hosting or please contact your hosting support for this issue.
After adding staff or student if no email is receiving or there is no any email send by system then your email setting is not configured properly so system is unable to send any email. To configure email please check this article.