The evaluation of error lines that are written to the error monitor does not work as described in VAC 3.0x.
For the SOM-Compiler, for example, setting the error template will not help/function correctly.
The code included will show you how you can force the error output for your tool to match the standard error template %f(%i): %t which will be evaluated correctly.
I have done this for the SOM compiler sc.exe.
Please note that the code will only work if the wrapper (sc2msg.exe) and the tool (sc.exe) are of the same prog type (in this case they are both WINDOWCOMPAT).

The code comes without warranty, use at your own risk.