I understand your frustration; I think it is a bug they have to correct has it could be done using some other Rhinocommon tool. CircleFit was introduced in SR2 in 2018 surely after Grasshopper component was done. See @dale answer here
“Circle Fit” is using Plane.FitPlaneToPoints then A = Sphere.FitSphereToPoints(P);
https://developer.rhino3d.com/api/rhinocommon/rhino.geometry.sphere/fitspheretopoints
Other bug with this method