One of the recurring irritants of importing STL files into CAD applications is the tendency of the mesh to show up at some distance from the CAD origin.
Even those who are experts in FreeCAD are slowed down by this.
This video explores two different workflows, one using the Manipulator Workbench.
Many of you would have gone down lots of rabbit-holes on this. I found a singular combination of toggles and selections that gets bodies derived from a STL mesh into a position of your choice. Mind you you still have to do some extreme zooms to ensure correct identification of the reference and body to move.