that is correct, you have to look into file DefaultEngine.ini to see how channels ECC_GameTraceChannelX map to your custom channels.
+DefaultChannelResponses=(Channel=ECC_GameTraceChannel1,DefaultResponse=ECR_Ignore,bTraceType=True,bStaticObject=False,Name="Landscape")
+DefaultChannelResponses=(Channel=ECC_GameTraceChannel2,DefaultResponse=ECR_Ignore,bTraceType=True,bStaticObject=False,Name="Blockable")
Reason why i provided given code is that to know how these ETraceTypeQuery map to ECC_GameTraceChannel, because I scrached my head for a while with theses channels and how they map