As you have discovered the electrics are different between the coupe and the roadster.
The roadster also have controls on the rear of the seat.
The roadster seats also have an auto electrical mechanism which slightly tilts the passenger seat when the roof is operated.
Best to swop like for like to save all the aggro.
The HR electrics are also different to the DE, as are UK model and JDM.
I am not saying that it can't be done, but there is no conversion kit for this as far as I know.