I've exported point cloud scan data in RCP format and attached as a reference in Civil3D 2016. It's coming in about 4.4 feet shifted to the southwest. This difference is much smaller than the scaling of state plane grid to ground so that doesn't seem to be the issue. However, I've exported in LAS format and it imports in the correct position in C3D yet of course the cloud points then are all white and fairly useless unlike the RCP format which is fully colorized as displayed in TBC.
This is through a Recap Pro 2019 license.