To follow up, when you look up the part number of the R1200S wheel speed sensor, there is no fitment for any RTs of similar generations, only the HP2s and some F and G bikes. Looks like it may have to be a sensor swap no matter what.
https://parts.bmwmotorcycle.com/p/BMW__/Wheelspeed-sensor/42766085/34527687528.html
Seems like you're stuck trying to get the canbus to read the wrong wheel speed sensor correctly. The only other option would be to rebuild the S final drive with RT gearing so the original sensor would work.
Also, who remapped your ECU?