They aren’t specifically listed in any of ASRock’s QVL reports for the motherboard, but reports from other X470 Taichi owners suggested they work just fine. My testing under Windows confirm these reports.
If I’m following this discussion correctly, it appears as though EDAC support for Zen 2 processors is in the process of of being accepted into the kernel. Which almost certainly means it doesn’t exist in the kernel I’m using. Could also explain why other users with Zen/Zen+ CPUs get full EDAC output from dmesg; support was added for those processors a while back.
Somewhat related: proper temperature reporting for Zen 2 won’t be added until 5.4