Having just had a lost bag issue with CX I know what OP means about not having a tracing number. When I filed my report in the baggage hall (at an outstation) they took down the tag number for the missing bag but did not give me a 10-character file reference that works for the tracing website. They said first they would figure out where the bag was based on when it had last been scanned and then if it was going to take more than a day to reach the destination airport they'd give me a file number.

Also, reaching the baggage office at the outstation (not Vietnam) was a nightmare. They rarely picked up any of the three local numbers they gave me -- it took me repeated attempts over two days to talk to anyone -- and they didn't respond to emails or call me back when they said they would. Posters glibly pointing the OP to web info probably haven't been in this hades before!