Interesting workaround. I don't have any CX segments but was able to access via amadeus PNR.
I ended up getting 2 emails from CX. One showed my originally ticketed itinerary and the next email showed my current one after I had made changes a month ago.

However, trying to pull up different DONE4 tickets (also lacking CX segment) did not work via Cathay.... so YMMV.