Irrespective of MT, CVT, AT, etc. If shifting from D to R, or R to D, R to first gear or first gear to R, the car should stop completely or come to an almost standstill, otherwise you may damage the transmission in the long run. AT / CVTs have pins which get locked and they can get damaged, if not stopping completely while changing from R to D, etc. And these are difficult to repair.
Even in case of MT, if you do not stop completely or come to an almost standstill, you may hear some grinding noise from the gearbox, meaning non smooth shifting, while shifting from R to IST gear, or otherwise.