My understanding (correct me if I'm wrong) is that the current version of RadarBox never downloads the ICAO type code from the server, it simply uses the value that it finds in NavData.db3 (which an individual RadarBox user can edit if he/she so desires).
I don't understand why that seems to be causing confusion over how the process works.
For the above to change will necessitate a new release of RadarBox and/or an updated NavData.db3, so it will be fairly obvious to all when that happens.