It has never been. The F lounge was just a small room inside the J lounge when CX used BA lounge. You should be boarding from the business lounge to A4 or A6. Sometimes passengers still needed to walk to other boarding gates if A4 and A6 were occupied.
CX had its own SFO lounge for probably 3 years. It is not next to any gate. You cannot board from the lounge. If the aircraft parks at Gate A3, then it is just a short walk.