If you want Jung So Min back in S2, she will have an ENTIRELY different personality from the current Mudeok (who has Naksu's soul). Unless writers plan to keep it a secret of her appearance in S2 by planning to use as Mudeok still with Naksu's soul and Naksu's body having Buyeon's soul being preserved or whatever.
For those who are concerned about Go Yoon Jung acting like So Min if Naksu's soul is to return to her original body, she doesn't need to copy Mudeok's accent, tone nor her behavior since she doesn't need to pretend as a maid anymore. She's back to her original body as Naksu with a cold aura.
For those who are concerned about Go Yoon Jung acting like So Min if Naksu's soul is to return to her original body, she doesn't need to copy Mudeok's accent, tone nor her behavior since she doesn't need to pretend as a maid anymore. She's back to her original body as Naksu with a cold aura.