P389: your curiosity is valid & something I share.
Given the previously-announced indication that the right-hand engine was likely the first to flame-out (with 12-15 minutes fuel remaining for the left-hand), one might expect the aircraft (if uncontrolled) to have entered the water right-wing down.
If the right-hand flaperon was fully down so as to compensate for this bank (and the flaperon would have been largely ineffective with a dead engine ahead), it is likely to have been promptly detached on contact.
So far, the bits we have are from the right...
It may be tricky to assign the RR logo debris to left or right side, given that the fragment appears to be relatively small.
Dean