The "Mirror Shield Chest" and "Beamos Ledge Chest" should be in simple logic with the first key.
Doing my best to make it clear but feel free to ask if I have to explain something further:
- take the intended path up to the first pillar room
- drop down any one of the holes
- move to the room east and hit the switch
- move over the lowered blocks and back up staircase A into the Mirror Shield Chest Room where you can now get that chest
- drop down the hole onto the eastern ledge
- move north up to the Beamos Ledge Chest
The "Mirror Shield Chest" and "Beamos Ledge Chest" should be in simple logic with the first key.
Doing my best to make it clear but feel free to ask if I have to explain something further: