Well, it turns out that there were still a few flaws in it. In fact, Roan didn't think he could eliminate all of them. Sure, he had made many cultivation techniques in the past. However, he had never been able to create something as perfect as the system's Yin Yang Cultivation Technique. Let alone in Magali's case, where her meridians were all over the place.
While Magali tried the technique, Roan used his Divine Sense and Energy to verify her body. At the same time, he sent what he saw to Rean as the twins worked together to improve the technique. Of course, using Rean's knowledge of the body and Roan's knowledge of techniques as always.
Correcting the technique took a few minutes, but every try also took time. It wasn't before several hours later that Magali felt no side effects with it. "This is great! It's so smooth now!"
Roan sighed in relief after that. "That's good, then. It's quite unfortunate this job took way longer than I wished."