Hi Sanja
As per the documentation, the K2 Database cannot have a case-sensitive Collation. Only SQL_Latin1_General_CP1_CI_AS and Latin1_General_CI_AS is supported.
For additional business data databases, the collation requirements should not be that strict when using the SQL Server Service Type to integrate your business date.
I would suggest testing this with a case-sensitive Collation database using the SQL Server Service Type.
See the following documentation for more info on the SQL Server Service Type: https://help.k2.com/onlinehelp/k2five/userguide/5.1/default.htm#ServiceBrokers/SQLServer/SQL-Server-Service.htm
Regards,
T