So a hand held facing tool is more accurate than the CNC lathe that created the fork parts. I doubt it.
You’d be wrong, for two reasons. Firstly, the crown race isn’t usually cut on a CNC lathe, it’s usually a casting with the steerer tube pressed in – the steerer tube is drawn and butted, but often hasn’t been near a lathe. Then there’s paint in the way.
Secondly, the cutting tool is a very precise custom fit, and is in a guide that keeps it absolutely centred.
Another user on here will attest to the fact that even expensive bike parts sometimes need a final finishing with the correct hand tools to get them to fit properly…