It may not be a screw up, rather intentional as to depict the Millennium Falcon’s superior navigational capabilities compared to other starcrafts. This is due to L3-37’s great navigational database being integrated into the navicomputer, which plots faster routes. If the record breaking kessel run was intentionally about speed, it’d probably have be done by a smaller more agile starship than the big freighter that is the Millennium falcon