Despite it being seen in the Night 4 hallucinations in SATB, the appearance of Meta Knightmarion's face is not used very often in universe. He has the ability to hide his tentacles and eyes perfectly due to them being made out of ink, and with the power of his soul he is able to form his eyes inside of his body..... They only show up when he is either paranoid or traumatized.

Its the only way to perfectly represent his appearance accurately.