This may only confuse things further, @antonical, but I tried to unravel some of the mysteries of the #209* settings in Samsung Gen 6 R32 5kW + Sunamp Thermino (plenty of questions inside) - #8 by SarahH.
You also asked about #4053 earlier in this thread. This is used by the MIM to continuously reset the circulating pump PWM using the following equation:
New pump PWM o/p (%) = Current PWM output (%) + [(LWT - RWT - FSV#4052) x FSV#4053)].