There is a pattern in that area with the moving platforms. After you get past it, you'll reach the Hill's Boss. Defeat her and you will acquire the Sliding Tackle skill for Maya. Then return to the main castle hall, go up the stairs, go right, slide under the gate and descend the ladder and enter the mirror. This unlocks the gallery. Then buy the glass orbs from the witch to unlock all of the scenes.
Yes, you can use the debug/cheat keys. Press F9 to instantly get all skills. Then make your way back left to the castle area. Additionally, you may also press F10 to be put in front of the Beach Boss, then defeat him and open the chests to get the crimsom scepter. This item unlocks the ability to teleport around, so then just open the teleport screen and TP to the castle.