Steps to reproduce:

1. Apply template to MSSQL server that has the default instance

Result:

Template's "Get performance counters" script does not return required values for dependant items. 

These lines are to blame (example but there's a few similar): 

OBJECT_NAME = 'MSSQL$' + @@servicename + ':Buffer Manager'

Default unnamed instance returns:

SQLServer:Buffer Manager      

Versus named instance: 

MSSQL$MSSQLDEV:Buffer Manager

Expected:

Template handles this scenario correctly when instance is unnamed (default).