Indeed that Method iis the best way to do that IF your regions are closed (or closable within tolerance) AND coplanar (within tolerance). Shown the R5 SDK ref:
Other than that is a classic Clustering task using the Region Containment as criterium (kinda like ccx events are used for Clustering intersecting curves or Pt to Pt Distance for Clustering points or … etc etc).
That said Clustering can contain more than one criterium meaning endless combos (for intstance you can Cluster crvs that intersect only 2 times and their length is greater than X and they are open and …).
Notify if you want a C# that does that (it’s rather fast as well).