There is no gearbox change, other than the removal of snow mode on the 2019 models. There is a tiny physical change to the intake, and the intake control valve opens at a lower rpm.
No changes to the engine for Europe, same as the 2018 model (i.e. down on power compared to pre-2018 models).
There is no change to the rear diff, expect for South Korea which gets a lower drive ratio, for all RC F, not just track edition.