I'm making a version Chris Gochnour's sideboard Build a Contemporary Sideboard - FineWoodworking

The stand has Barnsley Joints where the legs meet the rails. It's a nice detail, and I'd like to try it, but I'm confused about one thing.
In the build article, Chris uses two cutting jigs, one for the tapered legs, and one for the rails. Like this:
Screen Shot 2022-12-07 at 8.19.52 am.jpg

What I'm unsure about, is how to produce the jigs so that the parts fit together perfectly with the mating pieces, after they've been flush trimmed on their individual jigs. For example, if the curves on each jig aren't identical, and the parts aligned precisely, then no doubt the curve where the two parts meet will be steppy or gappy?

Perhaps it is as simple as using a curve template to create the jigs in the first place. By clamping the two jigs bases down in the correct orientation (perpendicular to each other), then cut the curve into both templates at the same time with a circle template?

I feel I'm over thinking this, and perhaps missing something very obvious!