We booked our fall transpacific while on board an Alaska cruise last spring. We specifically chose to stay A2 so our room would be between floors of staterooms. In the fall our TA found a better deal and rebooked our room in doing so she took the upgrade to a A1. We ended up with good room (we think) but to answer your question TA's can definitely access the CC 's benefits as ours did it without us even asking.
Really enjoying the report so far love seeing how busy the sea days have been.