While the Kadomaru Pro corner cutter is possible one of the most satisfying stationary tools to action, turns out there is a much simpler solution for getting perfectly rounded corners of the exact MTG radius; I speculated about using the Cricut itself to cut rounded corners on previous posts, but never got the time to investigate deeply.

Luckily, Gabriel Grant came to my rescue and made a version of the MTG 2x3 Cricut template with the rounded corners built in! That is fully compatible with the template on the card-press side and current workflow, just instructs the Cricut to cut round corners over the same PDF.

I've added as an addendum to the tutorial mentioning this new development.