The last time I transited thru CPH was back in May last year when SQ got those funny flights to FCO which need to transit thru CPH. It took me about 20 minutes to get thru everything gate to gate. But keep in mind that this was pretty much the BEST case scenario with passenger volume much lower back then (nearly no line in immigration and security). Given how things are now I am really not sure 50 minutes is nearly enough.