brunos

Not sure I understand your itinerary and question.
It seems that you booked a FRA-KUL-FRA ticket with CX in P class. HKG is only a transit.
For some reason, you are ending in LHR on a separate BA ticket. Am I right?

Was the HKG-FRA CX flight cancelled and rebooked on LH codeshared by CX?
On days when CX289 operates it departs within 5 min of LH797 in November. Hence not a major scheduling change. But CX289 is faster than LH797, hence you should arrive some 50min later, hoping that it won't create problem for your BA flight to LHR.

With a P fare you will earn 0 avios and TP on CX, so there is no change if you are moved to LH.

LH A340 has been 2x2x2 in Business for quite a long time. It is not a great business seat and window seats do not have direct aisle access. But it is not the old 2x3x2 seats.