I think even "old" GGLs are labelled as Plat-Pro on board, as are all OWE, and that is what translates to the Group 2 boarding unless you are in F.
I have said previously but I have certainly had success just propelling myself forward when the CKs are called on domestics but I think that the staff were generally somewhat perplexed and just let me past- Finland Station's report makes me (somewhat) less likely to try that again....!

Whatever system the CK team (and I believe some ground staff) can use is a bit different and, all being well, should show GGL as "BA VIP" or something similar.
If there is a CK rep at the gate then it seems that they would expect you to be there and last time I flew (or more accurately, tried to fly) AA internationally I was called forward by name.
But then there was another "real" AA CK passenger on board so I am not sure if they would specifically have sent someone if it was just me.