Saw this. So this explains how Park Jin and his minions didnt recognize Naksu right away. She had a different build as Jin Mu mentioned. Ever since Part 1 ep1, they meticulously made her look "tall". Even the eye mole was part of the plan. (Sorry if this was already posted, havent keeping up with all the posts here. ) π
Healing took years for current JBY. So I guess healing takes time. And would come back to my initial answer - Naksu didnt do it on her own. Master Lee had to use his energy too.
https://twitter.com/ramblingsofafan/status/1605730190679744512?t=ABXW9pEUYHIXCr6MWbNMcQ&s=19