I don’t think the use case for arc support is the same as arcwelder pushes. Arcwelder is there to turn high resolution prints that would overwhelm the planner and serial interface of marlin into much fewer instructions which are then expanded by the planner.
Klipper would be transmitting the same number and rate of instructions between the pi and arduino having already done the planning in python.
It maybe has a use for smoothing lower-res gcode into less precise but smoother curves, but you’d be setting arcwelder differently?
Please correct me if I’m wrong here, I used arcwelder a lot on marlin, but I’ve not had a reason other than smoothing gcode from a low res stl when using klipper