After tracking Johnny to the local bar and finishing up business there, you will need to travel to the cinema. The only issue with that task is that the road to the cinema has eroded and there is a large void between you and your objective.
For the "My God, It's Full Of Stars!" achievement, all you need to do is jump right into the void and kill yourself. The achievement will unlock right away! When it does, either return to the Home Screen of your Xbox One or pause the game and reload your latest checkpoint in order to now work on "Now That's Thinking With Shadows."
For this second achievement, you will need to power up the searchlight in the middle of the road with three Luminaries. Didi will shine the searchlight on the nearby sign and you must clear this platforming segment without failing in order to obtain the achievement. If you do mess up for whatever reason, remember to quickly pause your game and reload the checkpoint in order to try again. Take note that during this puzzle, you will need to jump from one shadow to the other. When you perform this jump, you will "unshift" from the shadow. Quickly tap the shift trigger again when you are about to land on the other shadow, or else you will fall to your death.