Here are some info: CX873 would be AA8931 and CX870 will be AA8929. HKG-ICN flights are not codeshared with AA so they don't have AA flight numbers.

I don't really understand what proper crediting means by OP. If OP booked flights under the CX code, then the EQMs and EQDs would be calculated using the CX chart, which is based on the distance flown and the booking class (earning nothing if booking class is below H, 20%-25%EQD and 1/1.5EQM per mile flown for higher fares). Whether that flight is codeshared with AA is not relevant here.