Sorry for the late reply.
I understand that this is a complicated problem.
Our office works all over the US, but one of the primary coordinate systems is:
NAD83 Texas State Planes, South Central Zone, US Foot
It may be possible for me to move data exported from Forma into Revit into its correct coordinate location based on property lines. However GIS property lines are not as accurate as Civil provided. But, I will experiment with this.
We are architects, and we rely upon Civil engineers to provide initial site data for all team members. Civil will supply legal definitions of property lines. They locate all utilities (including underground), trees, buildings, site work (sidewalks, walls, curbs) accurate to the 100/th of an inch. GIS data from cities is never as accurate as this, and will never be. Hopefully, you guys are working with Civil engineers as they can often translate data from one coordinate system to another. On one recent project, the Engineer provided county line was about 10' off of, but parallel to the GIS line provided by the state. We have to rely upon the Engineer as his license depends on accuracy, whereas the state doesn't have a requirement such as this.
As for the coordinate systems, my understanding is that Civil will always work in a "local" coordinate system as it is more accurate than lat/long coordinates. This is why there are thousands of coordinate systems around the world. However, there are formulas to convert from one to another. Way over my head though!