I simply use the Trakt addon. Create an account on trakt.tv and fill in your credentials in the addon on your RP3.
Do a library scan and sit back, it will take some time to set all the watched statuses in your account.
After it is done, i would recommend a reboot, it will do another full trakt update. Then you are done.
Then replace the RP3 for the Vero, install the addon and fill in your credentials, it will update all watched statuses in Kodi