Sorry, I should have been clearer - you are quite correct: the CX Arrivals lounge is available to arriving CX/KA J & F pax plus MP Gold, Diamond and OWE (on CX), not general CX pax. I didn't reiterate this because the OP is on a CX J ticket.
But yes, transiting pax (as per the above qualifications) can use the Arrival lounge if their transit is 4 hours or more.
https://www.cathaypacific.com/cx/en...g-kong-international-airport/the-arrival.html
I was going to use it earlier this month but my incoming was delayed, so transit time ended up less than 4 hours.
In the event, I didn't even look for it - just had a shower at the QF lounge and whiled away the time exploring the various areas of The Wing.
Excellent food, wine, champers and service. I highly recommend the Noodle Bar and the food in the other areas was very good as well.
I'll explore (in more depth) one of the other CX lounges on the way back in August, including the Arrival if I can change one of my flights.