It must be linked to the GCMS system where visa officers provide inputs. Then the data flows to different system including GCKey, ECAS & more unknown to us.
Major updates and major decisions are made by IRCC main office, but the Visa Office does most investigations and communication with the applicant. I might not be 100% sure of me answer but I know for sure it isn't only one office making decisions.
But as the colleague said detailed info of how it's being transferred from officer to officer can be proof in the GCMS notes.