Sorry for the late reply! I just wanted to give myself a proper weekend break – and now with the summer heat kicking in, it’s getting harder to focus 😅
About the mother’s room: there's a crack on the floor near the right side of the door — that’s where you need to interact. If it’s too hard to spot, alright – I’ll try to make it more noticeable.
As for the Rubik’s Cube: You can rotate only the front, top, and right layers with the left mouse button. To rotate the whole cube and change the sides, you need to hold the right mouse button and move the mouse in any direction.